Whether you want to snorkel, kayak, surf, or just go for a swim, Makaha allows you great conditions to do it all. The beach is spacious, the usually sunny conditions of Oahu's west side make the water temperature great, and there are lifeguards watching over in case of anything. Incredibly lively sea life like dolphins, sea turtles, and Hawaii's many colorful fish also make an appearance.
Pro tip: The current can vary, so make sure that you're always aware of any signs before you head into the water. Also, park close to the beach, and not in the lot across the street - it'll be easier to keep an eye on your car.