diff --git a/src/runtime-three/first-person-navigation-controller.ts b/src/runtime-three/first-person-navigation-controller.ts
index 75cc31bd..53b22ca9 100644
--- a/src/runtime-three/first-person-navigation-controller.ts
+++ b/src/runtime-three/first-person-navigation-controller.ts
@@ -11,6 +11,14 @@ import {
   resolvePlayerStartActionInputs,
   resolvePlayerStartLookInput,
 } from "./player-input-bindings";
+import {
+  CLIMB_INPUT_ACTIVE_THRESHOLD,
+  CLIMB_SPEED_METERS_PER_SECOND,
+  computeClimbPlaneMovement,
+  shouldEnterClimbing,
+  shouldExitClimbing,
+  type RuntimePlayerClimbSurface
+} from "./player-climbing";
 import {
   createIdleRuntimeLocomotionState,
   stepPlayerLocomotion
@@ -121,6 +129,8 @@ export class FirstPersonNavigationController implements NavigationController {
   private jumpBufferRemainingMs = 0;
   private coyoteTimeRemainingMs = 0;
   private jumpHoldRemainingMs = 0;
+  private climbSurface: RuntimePlayerClimbSurface | null = null;
+  private climbLatchBlocked = false;
 
   activate(ctx: RuntimeControllerContext): void {
     this.context = ctx;
@@ -225,6 +235,8 @@ export class FirstPersonNavigationController implements NavigationController {
     this.jumpBufferRemainingMs = 0;
     this.coyoteTimeRemainingMs = 0;
     this.jumpHoldRemainingMs = 0;
+    this.climbSurface = null;
+    this.climbLatchBlocked = false;
     this.previousTelemetry = null;
     ctx.setRuntimeMessage(null);
     ctx.setPlayerControllerTelemetry(null);
@@ -267,6 +279,8 @@ export class FirstPersonNavigationController implements NavigationController {
     this.jumpBufferRemainingMs = 0;
     this.coyoteTimeRemainingMs = 0;
     this.jumpHoldRemainingMs = 0;
+    this.climbSurface = null;
+    this.climbLatchBlocked = false;
   }
 
   update(dt: number): void {
@@ -297,6 +311,12 @@ export class FirstPersonNavigationController implements NavigationController {
       );
     }
 
+    if (
+      this.stepClimbing(dt, inputState, playerMovement, this.yawRadians)
+    ) {
+      return;
+    }
+
     const locomotionStep = stepPlayerLocomotion(
       {
         dt,
@@ -397,6 +417,8 @@ export class FirstPersonNavigationController implements NavigationController {
     this.jumpBufferRemainingMs = 0;
     this.coyoteTimeRemainingMs = 0;
     this.jumpHoldRemainingMs = 0;
+    this.climbSurface = null;
+    this.climbLatchBlocked = false;
     this.inWaterVolume = false;
     this.inFogVolume = false;
     this.updateCameraTransform();