It is important to be careful when swimming with a hair weave, especially if glue has been used to help hold your extensions. Chlorine and other chemicals in the water--as well as salt from the ocean--can break down the glue and build up in the braids. This is not healthy for your hair and it can loosen your weave. Although it is best to stay out of the pool and ocean while you have extensions, wearing a swim cap will help prevent chemicals and salt from saturating your hair and damaging your weave braids and glue.
Braid your hair in large sections and pile on your head. This will make it easier to put on the swim cap.
Put on a swim cap. It won't completely protect your hair, but it will go a long way toward protecting your weave.
After swimming, remove the large braids you made to put your hair under the swim cap and take a warm shower. Be sure to completely saturate your hair, and pay close attention to the weave braids.
Shampoo and condition your hair and rinse very well. Repeat if you think your hair really soaked up the pool water.
Dry your hair thoroughly with a low-heat blow-dryer. Check your weave; if any of the weave braids feel loose or if you find a lot of shedding, see your hairstylist to have it repaired.