The object and accompanying animations for Lara are in the TEN base WAD, which comes with the general TEN download package.
If you wish to create a drowning effect as seen in Tomb Raider III, you need to assign a “water” footstep sound to the texture and attach a death flag to the specific sectors where you want Lara to drown. To gain more insight on this process, refer to this tutorial available HERE.
New graphic elements were added for water wakes and ripples.