Oceans not swimmable

My sims can't perform any actions in the water. No snorkeling, swimming, diving, boating or anything. The only interaction available is at the waters edge - you can still "gather water" or "wade in water." Nothing else works though so there are whole sections of Sulani that can't be reached because the sims have to swim to them. Plus mermaids keep drying out because they can't get in the ocean.