Normally our tropicals themes are very tied to the sea, and rightly so.  When one thinks of tropical shirts they think of sitting on the beach, relaxing with a drink in hand.  This shirt evokes something a little different, though no less tropical.  My first thought upon seeing this was sitting in a boat travelling down the Amazon River.
 
It's not what you'd normally think of, but I think it all checks out.  Warm weather, plenty of water, there are even dolphins!  Of course, your drink of choice can be taken any where with you.  With the swirling blues and greens of this tropical, how can you possibly disagree?