ideal game state is Marincess Aqua Argonaut protected by Marincess Battle Ocean (having been summoned using Marincess Crystal Heart), Barrier Statue of the Torrent on the field, and some combination of Toadally Awesome on board and Marincess Wave plus some hand traps in hand.
use Marincess Blue Slug and Marincess Sea Angel to go into Marincess Coral Anemone, use Battle Ocean to equip Slug and Angel to Anemone, use Adularia of the June Moon's first effect to special summon itself since you have a face-up card in your S/T zone, use its second effect to send Slug and Angel to grave to mill Torrent, use Anemone to revive Torrent. remaining resources should go toward Aqua Argonaut and Toadally.
Marincess Coral Triangle sadly needs Marincess monsters specifically, so it's a tiny bit harder to get out of you use Adularia and thus searching Wave can be slightly tricky. you can always sacrifice going into Crystal Heart to bring out Aqua Argonaut if you would rather have Wave instead, since it also protects Argonaut (as well as the rest of your monsters) from your opponent's card effects if you use it.
Silent Sea Nettle is an extra body and great recovery with its grave effect.
Marincess Blue Tang's targets in order of priority are: Marincess Sea Horse, Marincess Mandarin, Marincess Basilalima, whatever other Marincess monster you want to add back to your hand later (with Marincess Springirl and Marincess Sleepy Maiden having effects to special summon themselves from hand).
chain Tang's and Springirl's floating effects when they're used for a WATER Link Monster to Slug's and Angel's on-summon effects to make sure they resolve properly. chain Battle Ocean's equip effect (which is not once per turn) to Anemone's extremely valuable floating effect to make sure that goes off as well.
always use Cynet Mining if you draw it even if you don't need it to bait Ash Blossom & Joyous Spring.
just keep swimming or whatever 🌊