If you are a "normal" heterosexual, you probably would be so obsessed with "sex" that it would be absolutely unthinkable to have your own naked body seen by anyone, whether of the same sex or another, and regardless of the other person's "sexual orientation."

If you've achieved an adult perspective on sex (not a normal thing to do in the US) you'd bathe/shower to get clean, and the presence or absence of others (especially, but not limited to persons of the same sex or/or sexual orientation) doing the same thing at the same time would be totally inconsequential to you, so bathing/showering "together" would be a very ordinary thing to do.

Skinny dipping can be fun, in same or mixed sex groups, and "sexual overtones" can be entirely optional in any mixture of participants, just as when everybody wears bathing suits; but it can be rendered completely "unenjoyable" by the presence of JUST ONE PERVERT (no intentional reference to the troll who started this) who thinks there's "something nasty" about being human, or that "nobody can see nakedness without being uncontrollably obsessed with sex."

Grow up, or leave the party until you get over your own obsessions, while the grownups perform their ablutions. If it bothers you, just don't look.

John