My girlfriend has an open wound and she dipped it in the ocean in the bahamas is she gonna get sick?

Most likely Not: However that depends upon the type of wound and what she is doing to treat it. It also depends upon where the wound is on the body. Make sure to clean and disinfect the wound after going in the water. Start with simple soap and water, follow with an antiseptic treatement from the pharmacy (avoid iodine/betadine) and then clean dressing. If she gets fever, redness,swelling, wound looks bad, go2 ER.

Watch for infection: Open wound are prone to infection, especially in ocean water or lake water where you do not know what kind of bacteria may be present. Keep the wound clean, use a topical antibiotic. If signs of infection develop, see your doctor.

Wound care: Not necessarily. Keep the area clean with warm water and soap. The ocean is notoriously filled with bacteria though, so keep a good eye on it. If it looks like it's getting infected, get it evaluated immediately. Signs of infection include warmth, redness, and increased drainage.