It is, Poseidon's temple was there and I had to go there to avoid my brothers being killed by a stupid and pathetic mind trick.

[And to rescue Athena and fight Poseidon. But everyone knows what was the thing Ikki did first upon reviving, chase his brothers and save them.]

I can't breath under water, though, but I can hold my breath more than normal people do. So sure, I will help, though I take that now it's pretty pointless.

[Kind of a given since he went so far inside the sea without the use of a shortcut or the help of one of Poseidon's minions.]