Be aware of chlorine from swimming pools and salt in the air from beaches. Both chlorine and salt can damage hair, make it look dull and lose its shine, lead to frizz and split ends. A spray conditioner every now and then can help get some of the shine back. It is important that you thoroughly wash your hair in the shower after a swim in the swimming pool or in the ocean, and of course, use conditioner. If that's not possible, try to wear a plastic cap when you get into the water.