Shallow enough water = Swimming in air

Good evening Engineers, tonight I present to you my latest installment of water terrain bugs: The Feature from the Black Lagoon. It seems if you’re moving around in shallow enough water and go idle near the edge, you’re able to swim around in the air

Step 1) Open repro file
Step 2) Advance towards the water
Step 3) Trigger swimming then go idle
Step 4) Observe

I wouldn’t blame anyone for considering this low priority because I’m unsure when a user will actually need a specific terrain water setup like this, but I wanted to do my due diligence as I couldn’t find the bug reported elsewhere. I stumbled upon this bug in a random game and adjusted the baseplate by 0.05 stud increments until I found the sweet spot. Also I’m pretty sure I’m the first to upload a repo with the new baseplate :swag:

FeatureFromTheBlackLagoon.rbxl (37.5 KB)


Note that in the video we see a brief cameo of the water/atmosphere bug I reported last summer, which can be found here: Bug with terrain water & looking through it - Bug Reports / Engine Bugs - DevForum | Roblox

I bring this up because it still persists and actually impacts aspects of designing terrain map features such as waterfalls

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Agreed, this is a concerning issue as I have played games where the water level is right under the floor and I swim on the floor (water under the floor isn’t visible). Quite odd.

I have had rare reports of this issue in my game aswell.

People would randomly be stuck swimming in mid air around their base after teleporting back from an area with water.

I had noticed this discontinuity generating cubes of terrain water with the API instead of using the terrain tool a few months ago: it was exactly the behavior you would expect if the body of water was 2 studs higher than the visual mesh.

Update: I was not able to reproduce this case and the associated games seem to no longer be affected by this fillblock case. (Though I was able to reproduce OP’s bug with the repro)

Thanks for the report! We’ve filed a ticket to our internal database and we’ll follow up when we have an update for you.


Got the same problem in my game and it’s causing a lot of problems, did you find a temporary solution to this problem or we got to stay like this for a very long time before roblox actually fixes it?

The only solution I can think of is to surround affected areas with invisible barriers, and this is a band-aid solution at best. The gifs you provide here tell me that the problem is worse than I originally thought - you’re quite literally swimming upwards into the air

It’s still happen to my game and even Brookhaven RP