diff --git a/tachys/src/html/element/custom.rs b/tachys/src/html/element/custom.rs
index 9ed1901c73..42d618b7a6 100644
--- a/tachys/src/html/element/custom.rs
+++ b/tachys/src/html/element/custom.rs
@@ -9,8 +9,9 @@ where
     E: AsRef<str>,
 {
     HtmlElement {
+        #[cfg(debug_assertions)]
+        defined_at: std::panic::Location::caller(),
         tag: Custom(tag),
-
         attributes: (),
         children: (),
     }
diff --git a/tachys/src/html/element/elements.rs b/tachys/src/html/element/elements.rs
index fc804d67d7..67b5926c6f 100644
--- a/tachys/src/html/element/elements.rs
+++ b/tachys/src/html/element/elements.rs
@@ -25,10 +25,11 @@ macro_rules! html_element_inner {
 
             {
                 HtmlElement {
+                    #[cfg(debug_assertions)]
+                    defined_at: std::panic::Location::caller(),
                     tag: $struct_name,
                     attributes: (),
                     children: (),
-
                 }
             }
 
@@ -55,10 +56,17 @@ macro_rules! html_element_inner {
                         At: NextTuple,
                         <At as NextTuple>::Output<Attr<$crate::html::attribute::[<$attr:camel>], V>>: Attribute,
                     {
-                        let HtmlElement { tag, children, attributes } = self;
+                        let HtmlElement {
+                            #[cfg(debug_assertions)]
+                            defined_at,
+                            tag,
+                            children,
+                            attributes
+                        } = self;
                         HtmlElement {
+                            #[cfg(debug_assertions)]
+                            defined_at,
                             tag,
-
                             children,
                             attributes: attributes.next_tuple($crate::html::attribute::$attr(value)),
                         }
@@ -118,14 +126,16 @@ macro_rules! html_self_closing_elements {
         paste::paste! {
             $(
                 #[$meta]
+                #[track_caller]
                 pub fn $tag() -> HtmlElement<[<$tag:camel>], (), ()>
                 where
 
                 {
                     HtmlElement {
+                        #[cfg(debug_assertions)]
+                        defined_at: std::panic::Location::caller(),
                         attributes: (),
                         children: (),
-
                         tag: [<$tag:camel>],
                     }
                 }
@@ -138,7 +148,6 @@ macro_rules! html_self_closing_elements {
                 impl<At> HtmlElement<[<$tag:camel>], At, ()>
                 where
                     At: Attribute,
-
                 {
                     $(
                         #[doc = concat!("The [`", stringify!($attr), "`](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/", stringify!($tag), "#", stringify!($attr) ,") attribute on `<", stringify!($tag), ">`.")]
@@ -151,13 +160,18 @@ macro_rules! html_self_closing_elements {
                             V: AttributeValue,
                             At: NextTuple,
                             <At as NextTuple>::Output<Attr<$crate::html::attribute::[<$attr:camel>], V>>: Attribute,
-
                         {
-                            let HtmlElement { tag, children, attributes,
+                            let HtmlElement {
+                                 #[cfg(debug_assertions)]
+                                 defined_at,
+                                tag,
+                                children,
+                                attributes,
                             } = self;
                             HtmlElement {
+                                #[cfg(debug_assertions)]
+                                defined_at,
                                 tag,
-
                                 children,
                                 attributes: attributes.next_tuple($crate::html::attribute::$attr(value)),
                             }
diff --git a/tachys/src/html/element/mod.rs b/tachys/src/html/element/mod.rs
index 388eb3805b..e1581ca7c8 100644
--- a/tachys/src/html/element/mod.rs
+++ b/tachys/src/html/element/mod.rs
@@ -1,6 +1,8 @@
+#[cfg(debug_assertions)]
+use crate::hydration::set_currently_hydrating;
 use crate::{
     html::attribute::Attribute,
-    hydration::Cursor,
+    hydration::{failed_to_cast_element, Cursor},
     renderer::{CastFrom, Rndr},
     ssr::StreamBuilder,
     view::{
@@ -24,10 +26,14 @@ pub use custom::*;
 pub use element_ext::*;
 pub use elements::*;
 pub use inner_html::*;
+#[cfg(debug_assertions)]
+use std::panic::Location;
 
 /// The typed representation of an HTML element.
 #[derive(Debug, PartialEq, Eq)]
 pub struct HtmlElement<E, At, Ch> {
+    #[cfg(debug_assertions)]
+    pub(crate) defined_at: &'static Location<'static>,
     pub(crate) tag: E,
     pub(crate) attributes: At,
     pub(crate) children: Ch,
@@ -36,8 +42,9 @@ pub struct HtmlElement<E, At, Ch> {
 impl<E: Clone, At: Clone, Ch: Clone> Clone for HtmlElement<E, At, Ch> {
     fn clone(&self) -> Self {
         HtmlElement {
+            #[cfg(debug_assertions)]
+            defined_at: self.defined_at,
             tag: self.tag.clone(),
-
             attributes: self.attributes.clone(),
             children: self.children.clone(),
         }
@@ -75,14 +82,16 @@ where
 
     fn child(self, child: NewChild) -> Self::Output {
         let HtmlElement {
+            #[cfg(debug_assertions)]
+            defined_at,
             tag,
-
             attributes,
             children,
         } = self;
         HtmlElement {
+            #[cfg(debug_assertions)]
+            defined_at,
             tag,
-
             attributes,
             children: children.next_tuple(child.into_render()),
         }
@@ -103,11 +112,15 @@ where
         attr: NewAttr,
     ) -> Self::Output<NewAttr> {
         let HtmlElement {
+            #[cfg(debug_assertions)]
+            defined_at,
             tag,
             attributes,
             children,
         } = self;
         HtmlElement {
+            #[cfg(debug_assertions)]
+            defined_at,
             tag,
             attributes: attributes.add_any_attr(attr),
             children,
@@ -229,8 +242,9 @@ where
         let (attributes, children) =
             join(self.attributes.resolve(), self.children.resolve()).await;
         HtmlElement {
+            #[cfg(debug_assertions)]
+            defined_at: self.defined_at,
             tag: self.tag,
-
             attributes,
             children,
         }
@@ -336,6 +350,11 @@ where
         cursor: &Cursor,
         position: &PositionState,
     ) -> Self::State {
+        #[cfg(debug_assertions)]
+        {
+            set_currently_hydrating(Some(self.defined_at));
+        }
+
         // non-Static custom elements need special support in templates
         // because they haven't been inserted type-wise
         if E::TAG.is_empty() && !FROM_SERVER {
@@ -349,7 +368,9 @@ where
             cursor.sibling();
         }
         let el = crate::renderer::types::Element::cast_from(cursor.current())
-            .unwrap();
+            .unwrap_or_else(|| {
+                failed_to_cast_element(E::TAG, cursor.current())
+            });
 
         let attrs = self.attributes.hydrate::<FROM_SERVER>(&el);
 
diff --git a/tachys/src/hydration.rs b/tachys/src/hydration.rs
index 5e631841ca..7f7cdd6245 100644
--- a/tachys/src/hydration.rs
+++ b/tachys/src/hydration.rs
@@ -2,7 +2,10 @@ use crate::{
     renderer::{CastFrom, Rndr},
     view::{Position, PositionState},
 };
-use std::{cell::RefCell, rc::Rc};
+#[cfg(debug_assertions)]
+use std::cell::Cell;
+use std::{cell::RefCell, panic::Location, rc::Rc};
+use web_sys::{Comment, Element, Node, Text};
 
 /// Hydration works by walking over the DOM, adding interactivity as needed.
 ///
@@ -95,13 +98,121 @@ where
         }
         let marker = self.current();
         position.set(Position::NextChild);
-        crate::renderer::types::Placeholder::cast_from(marker)
-            .expect("could not convert current node into marker node")
-        /*let marker2 = marker.clone();
-        Rndr::Placeholder::cast_from(marker).unwrap_or_else(|| {
-            crate::dom::log("expecting to find a marker. instead, found");
-            Rndr::log_node(&marker2);
-            panic!("oops.");
-        })*/
+        crate::renderer::types::Placeholder::cast_from(marker.clone())
+            .unwrap_or_else(|| failed_to_cast_marker_node(marker))
+    }
+}
+
+#[cfg(debug_assertions)]
+thread_local! {
+    static CURRENTLY_HYDRATING: Cell<Option<&'static Location<'static>>> = const { Cell::new(None) };
+}
+
+pub(crate) fn set_currently_hydrating(
+    location: Option<&'static Location<'static>>,
+) {
+    #[cfg(debug_assertions)]
+    {
+        CURRENTLY_HYDRATING.set(location);
+    }
+    #[cfg(not(debug_assertions))]
+    {
+        _ = location;
+    }
+}
+
+pub(crate) fn failed_to_cast_element(tag_name: &str, node: Node) -> Element {
+    #[cfg(not(debug_assertions))]
+    {
+        _ = node;
+        unreachable!();
+    }
+    #[cfg(debug_assertions)]
+    {
+        let hydrating = CURRENTLY_HYDRATING
+            .take()
+            .map(|n| n.to_string())
+            .unwrap_or_else(|| "{unknown}".to_string());
+        web_sys::console::error_3(
+            &wasm_bindgen::JsValue::from_str(&format!(
+                "A hydration error occurred while trying to hydrate an \
+                 element defined at {hydrating}.\n\nThe framework expected an \
+                 HTML <{tag_name}> element, but found this instead: ",
+            )),
+            &node,
+            &wasm_bindgen::JsValue::from_str(
+                "\n\nThe hydration mismatch may have occurred slightly \
+                 earlier, but this is the first time the framework found a \
+                 node of an unexpected type.",
+            ),
+        );
+        panic!(
+            "Unrecoverable hydration error. Please read the error message \
+             directly above this for more details."
+        );
+    }
+}
+
+pub(crate) fn failed_to_cast_marker_node(node: Node) -> Comment {
+    #[cfg(not(debug_assertions))]
+    {
+        _ = node;
+        unreachable!();
+    }
+    #[cfg(debug_assertions)]
+    {
+        let hydrating = CURRENTLY_HYDRATING
+            .take()
+            .map(|n| n.to_string())
+            .unwrap_or_else(|| "{unknown}".to_string());
+        web_sys::console::error_3(
+            &wasm_bindgen::JsValue::from_str(&format!(
+                "A hydration error occurred while trying to hydrate an \
+                 element defined at {hydrating}.\n\nThe framework expected a \
+                 marker node, but found this instead: ",
+            )),
+            &node,
+            &wasm_bindgen::JsValue::from_str(
+                "\n\nThe hydration mismatch may have occurred slightly \
+                 earlier, but this is the first time the framework found a \
+                 node of an unexpected type.",
+            ),
+        );
+        panic!(
+            "Unrecoverable hydration error. Please read the error message \
+             directly above this for more details."
+        );
+    }
+}
+
+pub(crate) fn failed_to_cast_text_node(node: Node) -> Text {
+    #[cfg(not(debug_assertions))]
+    {
+        _ = node;
+        unreachable!();
+    }
+    #[cfg(debug_assertions)]
+    {
+        let hydrating = CURRENTLY_HYDRATING
+            .take()
+            .map(|n| n.to_string())
+            .unwrap_or_else(|| "{unknown}".to_string());
+        web_sys::console::error_3(
+            &wasm_bindgen::JsValue::from_str(&format!(
+                "A hydration error occurred while trying to hydrate an \
+                 element defined at {hydrating}.\n\nThe framework expected a \
+                 text node, but found this instead: ",
+            )),
+            &node,
+            &wasm_bindgen::JsValue::from_str(
+                "\n\nThe hydration mismatch may have occurred slightly \
+                 earlier, but this is the first time the framework found a \
+                 node of an unexpected type.",
+            ),
+        );
+        panic!(
+            "Unrecoverable hydration error. Please read the error message \
+             directly above this for more details."
+        );
     }
 }
diff --git a/tachys/src/mathml/mod.rs b/tachys/src/mathml/mod.rs
index d7edd52a36..9d4cbc4052 100644
--- a/tachys/src/mathml/mod.rs
+++ b/tachys/src/mathml/mod.rs
@@ -22,10 +22,17 @@ macro_rules! mathml_global {
 				At: NextTuple,
 				<At as NextTuple>::Output<Attr<$crate::html::attribute::[<$attr:camel>], V>>: Attribute,
 			{
-				let HtmlElement { tag, children, attributes } = self;
+				let HtmlElement {
+                    #[cfg(debug_assertions)]
+                    defined_at,
+                    tag,
+                    children,
+                    attributes
+                } = self;
 				HtmlElement {
+                    #[cfg(debug_assertions)]
+                    defined_at,
 					tag,
-
 					children,
 					attributes: attributes.next_tuple($crate::html::attribute::$attr(value)),
 				}
@@ -46,10 +53,11 @@ macro_rules! mathml_elements {
 
                 {
                     HtmlElement {
+                        #[cfg(debug_assertions)]
+                        defined_at: std::panic::Location::caller(),
                         tag: [<$tag:camel>],
                         attributes: (),
                         children: (),
-
                     }
                 }
 
@@ -84,10 +92,17 @@ macro_rules! mathml_elements {
                             At: NextTuple,
                             <At as NextTuple>::Output<Attr<$crate::html::attribute::[<$attr:camel>], V>>: Attribute,
                         {
-                            let HtmlElement { tag, children, attributes } = self;
+                            let HtmlElement {
+                                #[cfg(debug_assertions)]
+                                defined_at,
+                                tag,
+                                children,
+                                attributes
+                            } = self;
                             HtmlElement {
+                                #[cfg(debug_assertions)]
+                                defined_at,
                                 tag,
-
                                 children,
                                 attributes: attributes.next_tuple($crate::html::attribute::$attr(value)),
                             }
diff --git a/tachys/src/svg/mod.rs b/tachys/src/svg/mod.rs
index 61cf66d909..12bfc0a79e 100644
--- a/tachys/src/svg/mod.rs
+++ b/tachys/src/svg/mod.rs
@@ -14,15 +14,16 @@ macro_rules! svg_elements {
                 /// An SVG element.
                 // `tag()` function
                 #[allow(non_snake_case)]
+                #[track_caller]
                 pub fn $tag() -> HtmlElement<[<$tag:camel>], (), ()>
                 where
-
                 {
                     HtmlElement {
+                        #[cfg(debug_assertions)]
+                        defined_at: std::panic::Location::caller(),
                         tag: [<$tag:camel>],
                         attributes: (),
                         children: (),
-
                     }
                 }
 
@@ -153,9 +154,12 @@ svg_elements![
 
 /// An SVG element.
 #[allow(non_snake_case)]
+#[track_caller]
 pub fn r#use() -> HtmlElement<Use, (), ()>
 where {
     HtmlElement {
+        #[cfg(debug_assertions)]
+        defined_at: std::panic::Location::caller(),
         tag: Use,
         attributes: (),
         children: (),
diff --git a/tachys/src/view/primitives.rs b/tachys/src/view/primitives.rs
index d32402f409..0441af882e 100644
--- a/tachys/src/view/primitives.rs
+++ b/tachys/src/view/primitives.rs
@@ -100,8 +100,8 @@ macro_rules! render_primitive {
 					}
 
 					let node = cursor.current();
-					let node = crate::renderer::types::Text::cast_from(node)
-						.expect("couldn't cast text node from node");
+					let node = crate::renderer::types::Text::cast_from(node.clone())
+						.unwrap_or_else(|| crate::hydration::failed_to_cast_text_node(node));
 
 					if !FROM_SERVER {
 						Rndr::set_text(&node, &self.to_string());
diff --git a/tachys/src/view/strings.rs b/tachys/src/view/strings.rs
index 902e4bbf73..df4719ed10 100644
--- a/tachys/src/view/strings.rs
+++ b/tachys/src/view/strings.rs
@@ -90,8 +90,10 @@ impl RenderHtml for &str {
         }
 
         let node = cursor.current();
-        let node = crate::renderer::types::Text::cast_from(node)
-            .expect("couldn't cast text node from node");
+        let node = crate::renderer::types::Text::cast_from(node.clone())
+            .unwrap_or_else(|| {
+                crate::hydration::failed_to_cast_text_node(node)
+            });
 
         if !FROM_SERVER {
             Rndr::set_text(&node, self);