diff --git a/geom/src/heightmap.rs b/geom/src/heightmap.rs
index 9c0f97e9..025403f7 100644
--- a/geom/src/heightmap.rs
+++ b/geom/src/heightmap.rs
@@ -442,7 +442,9 @@ impl<const RESOLUTION: usize, const SIZE: u32> Heightmap<RESOLUTION, SIZE> {
             .filter_map(|(x, y)| {
                 let chunk_id = (x as u16, y as u16);
                 let corner = vec2(x as f32, y as f32) * SIZE as f32;
-                let (t_min, t_max) = self.get_chunk(chunk_id)?.bbox(corner).raycast(ray)?;
+                let mut bbox = self.get_chunk(chunk_id)?.bbox(corner);
+                bbox.ll.z -= Self::CELL_SIZE; // give a bit of margin to avoid missing intersections when the heightmap is at the lowest
+                let (t_min, t_max) = bbox.raycast(ray)?;
                 Some((t_min, t_max))
             });
 
diff --git a/native_app/src/game_loop.rs b/native_app/src/game_loop.rs
index b777f7f8..be2450db 100644
--- a/native_app/src/game_loop.rs
+++ b/native_app/src/game_loop.rs
@@ -136,8 +136,13 @@ impl engine::framework::State for State {
             if let Some(ray) = ray {
                 let cast = map.environment.raycast(ray);
 
-                self.uiw.write::<InputMap>().unprojected = cast.map(|x| x.0);
-                self.uiw.write::<InputMap>().unprojected_normal = cast.map(|x| x.1);
+                let inp = &mut self.uiw.write::<InputMap>();
+
+                inp.unprojected = cast.map(|(mut proj, _)| {
+                    proj.z = proj.z.max(0.0);
+                    proj
+                });
+                inp.unprojected_normal = cast.map(|x| x.1);
             }
         }
 
diff --git a/native_app/src/inputmap.rs b/native_app/src/inputmap.rs
index 946f649f..6331962c 100644
--- a/native_app/src/inputmap.rs
+++ b/native_app/src/inputmap.rs
@@ -61,7 +61,7 @@ pub struct InputMap {
     pub act: FastSet<InputAction>,
     /// Mouse wheel delta
     pub wheel: f32,
-    /// Mouse position in world space on the terrain
+    /// Mouse position in world space on the terrain (max height 0)
     pub unprojected: Option<Vec3>,
 
     pub unprojected_normal: Option<Vec3>,
diff --git a/native_app/src/rendering/map_rendering/map_mesh.rs b/native_app/src/rendering/map_rendering/map_mesh.rs
index 630b3e3c..e870eea2 100644
--- a/native_app/src/rendering/map_rendering/map_mesh.rs
+++ b/native_app/src/rendering/map_rendering/map_mesh.rs
@@ -832,7 +832,7 @@ fn inter_pylon(
 ) {
     let interpos = inter.pos.up(ROAD_Z_OFFSET);
 
-    let h = unwrap_ret!(env.height(inter.pos.xy()));
+    let h = unwrap_ret!(env.true_height(inter.pos.xy()));
     if (h - interpos.z).abs() <= 2.0 {
         return;
     }
diff --git a/simulation/src/map/objects/road.rs b/simulation/src/map/objects/road.rs
index 75899879..5e4c224e 100644
--- a/simulation/src/map/objects/road.rs
+++ b/simulation/src/map/objects/road.rs
@@ -261,7 +261,7 @@ impl Road {
         interfaced_points
             .equipoints_dir(80.0, true)
             .filter_map(move |(pos, dir)| {
-                let h = env.height(pos.xy())?;
+                let h = env.true_height(pos.xy())?;
                 if (h - pos.z).abs() <= 2.0 {
                     return None;
                 }
@@ -331,13 +331,10 @@ impl Road {
             )
             .chain(std::iter::once(p.last()))
         {
-            let h = env
-                .height(pos)
-                .unwrap_or_else(|| {
-                    height_error = true;
-                    0.0
-                })
-                .max(0.0);
+            let h = env.height(pos).unwrap_or_else(|| {
+                height_error = true;
+                0.0
+            });
             contour.push(h);
             points.push(pos.z(h));
         }
diff --git a/simulation/src/map/terrain.rs b/simulation/src/map/terrain.rs
index 55ffb8e7..e57c14aa 100644
--- a/simulation/src/map/terrain.rs
+++ b/simulation/src/map/terrain.rs
@@ -73,7 +73,13 @@ impl Environment {
         me
     }
 
+    /// Returns the height of the terrain at the given position in meters, capped at 0
     pub fn height(&self, pos: Vec2) -> Option<f32> {
+        self.heightmap.height(pos).map(|x| x.max(0.0))
+    }
+
+    /// Returns the height of the terrain at the given position in meters, not capped at 0 (can be negative in water)
+    pub fn true_height(&self, pos: Vec2) -> Option<f32> {
         self.heightmap.height(pos)
     }