Select some interesting destinations from the many beaches, eating spots and other sights. Throw the snorkeling gear and swim suits in the back of the jeep. Some resorts and restaurants allow patrons to use some of their facilities such as pools. Most any beach invites some beachcombing or at least a stroll. A wade in the surf or a swim can be refreshing.
Marinas usually have showers, often for a fee.
There's nothing like a quick shower to rejunvenate a sailor or land traveler in the sweltering tropics. Take an extra top or two. A walking tour of the docks is almost always interesting. Use any good air conditioning to advantage by lingering a little longer there. Keep drinking liquids to avoid dehydration.