This compositing is based on stock images and brushes from deviantART:

 

Syllienna stock 4 by charligal-stock 
Finding Nemo by firenze-design 
misc bubbles element png by dbszabo1 
BUBBLE HEARTS brush by SweetCandyDreams 
Jellyfish 4 by Tasastock 
fish 1.2 by meihua-stock 
Aquarium 49 by Falln-Stock 
Water Texture by WisdomsPearl 
Diver by Dracofemi 
Underwater stock 17 by EvilHateYouAllStock