Add Old Navy boys swim trunks to sand castles, waves and sun and you've got a perfect match. Browse our large selection of durable boys swim trunks that are colorful, as well as functional. Relax knowing he will be comfortable in quick drying, easy pull-on boys swim trunks. Start the summer with Old Navy boys swim trunks in popular designs, colors and graphics that he'll love and you'll be able to spot in a crowd at the beach or pool.