>>530571152
this is an excellent question, and one i have spent some time studying
overall, its probably walrus or one of the newer water friends like manatee
the ocean friends do in fact have huge asses
while the big cats like white lion do have large rears they still get beat out handily by the blubber
some honorable mentions are >>530576636 and cali sea lion, they both have top tier asses that are barely smaller than the biggest, while wearing nice tight jeans too