Double click the green flag. Use the arrow keys to move the rubber duck. :P Now you can collect coins by swimming around, There isn't an exact goal for this game yet, I'm planning to make is a scrolling platform game. (in which you swim forever to try to collect the most coins until you hit an obstacle and the game ends)
Credit to @Cypher56 for the underwater engine. Font from @FontGod All art me (except the water), @-CyberArtist- WIP. Change log: created around 2015/2016 v.1. added coins - june 8, 2018 v.1.5 added boxes - june 18