That's the first time I've heard of Seapunk and I have to say I'm very unhappy that it isn't people dressed like sailors and playing rock and roll versions of sea shanties and original songs about mizzenmasts and boatswains and mermaids with seaweed hair.
I may have to start a band like that, steal the term sea punk, and release and EP called "Anarchy in the South Seas" or "Fresh Fruit for Scurvy" or "Greenland Calling." And possibly a Blondie cover "Call Me (Ishmael)"