Not only the skin but hairs can also be damaged very badly by ultra voilet rays.
Reason: under the influence of UV lights, water develops similar characteristics to hydrogen peroxide. The old  well known hair bleach.  Pigments are destroyed: as a result, the hair color becomes lighter and weaker, and the structure more porous.  For this process to begin  hairs are not needed to be wet, normal air and scalp moisture is sufficient.
The sun also removes the moisture present in the keratin in the hair, making it strawy and less elastic. However, UV rays damage all kind of hairs but  attention should be given on coloured, purmed and bleached hairs.

Few things which can protect your hairs on a sunny day on the beach is:

*A preparation with UV filters(spray, wet-gel and cream)

*An especially mild shampoo with moisture binders and grease replacers.

*Hair treatments and conditioners that adds moistures.

*A hat or ahead scarf to protect the hair, especially at midday, On the beach a cleverly tied headscarf and large sunhat is an smart idea to protect your hairs from sun.

*After swimming rinse the hairs with fresh water because salt and chlorine residue damage hair at very faster pace.

*Hair gel containing a UV filter helps to counter the detrimental effect of sunlight on hair color and quality.