Eldar are in like onesie pajamas right? Shouldn't cause them to sink as fast as a Marine wearing a tanks worth of armor.
Of course we like the water. How else would we sexily walk out of it, wearing the tightest speedo we could find, flicking our majestic locks?
As laid down in the Tenets of Cegorath, all Eldar must wear those mankinis Borat wears whilst swimming.
The formal term is a "slingshot bikini." And they're for women, to ruin the joke. Not a SFW topic to google, for the curious.
I'm fairly sure that at least the Eldar of the Exodite worlds must know how to swim. And don't forget - the eldar have to wash too.
Indeed, though to be precise the actual ritual is more akin to how a feline would groom itself. In this case it's properly done in a group of at least five. This can take hours. Hopefully.