Mermaid/man

For ocean themed, if anime is okay you can give Tsuritama and Taifuu no noruda a try :)

If you're okay with shounen ai, if not, you can just ignore this comment.

Merman anime: This boy caught a merman. Very colorful and beautiful and short.

manga: mister mermaid the art style is a bit old but the story itself is pretty nice and quite sad.

oh and orenchi no furo jijou. It's just a regular anime that's pretty funny and short.

THANK YOU!!!!!

one of the best I can recommend: https://myanimelist.net/anime/16067/Nagi_no_Asukara

http://www.mangago.zone/r/l_search/?name=merm - mermaid and men list of sea manga - I have only read one or two, but there are 11 pages worth, depending on the genre you want to read

http://www.mangago.zone/read-manga/erotic_fairy_tales_the_little_mermaid/
http://www.mangago.zone/read-manga/mermaid_and_the_magician/
http://www.mangago.zone/read-manga/kaizoku_to_ningyo/
http://www.mangago.zone/read-manga/junketsu_ningyo/
http://www.mangago.zone/read-manga/blue_eyes_hoshino_lily/
http://www.mangago.zone/read-manga/wagamama_na_ningyo_sama/
http://www.mangago.zone/read-manga/ningyo_no_ouji_sama/
http://www.mangago.zone/read-manga/wild_fish/
http://www.mangago.zone/read-manga/mermaid_syndrome/
http://www.mangago.zone/read-manga/ningyo_ouji/
http://www.mangago.zone/read-manga/evyione/

Sirens lament ლ(´ڡ`ლ) if u dont mind manhwa tho

I LOVE YOU ALL ┗( T﹏T )┛