I changed the ending from my original idea and focused more on the characters involved than in just finding a treasure. The explorer lives for the excitement of finding new places and taking cool pictures with the treasures she finds. She follows a map to a new treasure only to find that others have already found it - but this only makes it more fun for her.
Names just for fun:
Explorer - Gemma Stone
Mermen - (from left to right in the pool) Curls, Faben, Tules, and brothers Mirf and Larz.