Consider pairing a short sleeve shirt with black and white swim shorts to be both bold casual and seriously stylish. Does this ensemble feel too polished? Invite a pair of black leather sandals to switch things up. Those who are curious how to sport cool casual dressing in your thirties, you have your answer.
Why not opt for a short sleeve shirt and black and white swim shorts? As well as very practical, both of these pieces look amazing paired together. Black leather sandals will give a more laid-back spin to an otherwise traditional look. This pairing should clear any doubts you had about dressing casually as a 30-year-old man.