I recently discovered Tide Studio, an online platform for both established and emerging artists to sell limited edition prints curated around the theme of the ocean and water. Tide commits to donate 10% of every sale to the environmental charity Surfers Against Sewage, a campaign to protect the UK oceans. Each print comes with a hand signed certificate of authenticity.
See below for some of my favorite prints:

Image 1: Jonathan Niclaus, Miles Deep, Edition of 10, Printed on archival quality C-type Fuji matte paper, 11.5" x 16.5"
Image 2: Sarah Boyts Yoder, Lacuna 1, Edition of 5, Printed on archival quality Giclée Hahnemühle photo rag paper, 8.26" x 10.63"
Image 3: John Zabawa, Blue Homes, Edition of 20, Printed on archival quality Giclée Hahnemühle photo rag paper, 16 " x 20 "

Follow Tide Studio @tidestudio.co
Follow Jonathan Niclaus @jonathanniclaus
Follow Sarah Boyts Yoder @sarahboytsyoder
Follow John Zabawa @johnzabawa