I have question!

In panda3d sample i found example for add water, but panda3d have sample of water with underwater ?
or it’s possible in panda3d to add underwater environnement ?
Maybe i must to change camera color for add blue filter, play water sound and update physic but how to detect in game if i’m in earth or underwater and update physic ?
panda3d (with bullet ?) can be support multi-physic for create a world with earth gravity, underwater gravity and space gravity (disable gravity ?)

There are a lot of possibilities to do that. You can compare the character’s Z position with your sea level, or you can put a ghost collider (which doesn’t blocks you) to the places with water.

You can change gravity per object with bullet physics. This is how I’m doing a wall running in my game. So when the character is under water you can set his gravity to zero or some very low value.