Hi, i'm not really a speedrunner but i found another way to clip through the terrain than using the mobile vehicle bay, and i thought maybe this would help ! the problem is i don't know if it works for other people cause i don't have a really good PC to test it so maybe it's only because of my low framerate, i don't know...

This is how i do it: underwater, use the seaglide to run into a wall and at the exact moment your head hits the wall, look away fast and stop moving. if everything went good, you should be out of bounds. I don't really know why this is and if there are other "rules" for it, but with what i've tried so far i found that: this works best in safe shallows and kelp forest biomes, and at the looking away part the glitch only succeded when i moved my mouse horizontally. Also i don't know if this glitch works on a flat surface but i almost always nailed it when using cliffs or cave walls to do the trick.

it's only a suggestion and i don't really know the speedrun community, so i'm sorry if i'm bothering you... but maybe this will help !