What causes swimming and buoyancy physics?

Buoyancy force is mistuned so the character sinks or pops out, water drag is missing so movement is too fast, or the water surface detection is wrong, so swimming feels off or jitters.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Fix Swimming and Buoyancy Physics in a Game

Quick answer: Apply buoyancy based on submersion depth, add water drag to slow movement, switch to a swimming state with appropriate gravity, and detect the water surface cleanly.

Swimming that feels wrong is mistuned buoyancy and drag. Here is how to fix it.

How to fix it

1. Apply depth-based buoyancy

Scale the upward buoyancy force by how submerged the object is, so it settles at the surface instead of sinking or popping out. A constant force makes it bob or shoot up.

2. Add water drag

Water should slow movement. Apply drag while submerged so swimming and falling through water feel heavier than air. Without drag, the character moves through water as if it were not there.

3. Use a swimming state

Switch to a swimming movement state with reduced gravity and input-driven motion when submerged, and detect the water surface reliably so entering and exiting water transitions cleanly without jitter.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.

Reproduce it once with full context and the fix writes itself. The hunt is the expensive part.