Definition of "seapunk"

Seapunk's aqueous adherents, mostly in the Midwest but spreading fast […] have been characterized as goth mermaids, which certainly captures the look and feel: think turquoise-dyed hair and an embrace of all things oceanic, yay for steampunk jellyfish outfits.

2012 January 10, Marke B., “Mermaids vs. unicorns”, in San Francisco Bay Guardian

Many thought this understandably short-lived meme had died a watery death in 2011, but when Rihanna took to Saturday Night Live to perform Diamonds recently, with a full-on seapunk-influenced production, it got a new lease of life.

2012 December 14, Lucy Stehlik, “Seapunk: scenester in-joke or underground art movement?”, in The Guardian

She also lashed out at Azealia Banks, who dropped an explicitly seapunk video the same week, but Azealia's fine in my books. She’s always been into seapunk stuff, she “came from the internet” unlike Rihanna, she actually commits to and genuinely engages with the seapunk visuals (e.g riding dolphins) and they at least somewhat fit her song and attitude.

2013, Cameron Welch, "That's That Shit I Don't Like: The Year in Wackness", The Phoenix (UBCO), 7 January 2013, page 11 (online version)