Boys should swim shirtless because that is what they do. Plus, it saves them money and keeps them cooler. Boys would 've able to swim faster if the swam shirtless because they would be able to move around easier. Plus, boys also don't like the feeling of a wet shirt.
In water parks or in beach, swimming costumes are essential, especially swimsuits for boys and <a href="https://www.Dollboxx.Com.Au/collections/watermelon-melon-crush">Dollboxx</a> bikinis for girls. The bathing suits provide great comfort in water and prevents skin rashes which can occur by regular shirts and pants. As mostly swimming pools and water parks contains chlorine water ,it may also cause damage to our clothes.
I understand that some guys are uncomfortable with their body, and would prefer to cover up. Nothing wrong with that. While shirtless is the norm, It's totally fine with wear a swim shirt. Also, good for blocking the harmful rays, without layering on the sunscreen. If it makes you comfortable, Don't worry about what others think!