Sims can go far out in the ocean and snorkel to improve their Scuba Diving skill. Snorkeling or taking Scuba Diving classes is the only way to improve the skill enough to be able to actually dive. Snorkeling may turn up small collectibles such as shells. Sims can also snorkel in a swimming pool with sufficient space, although they will build the skill faster snorkeling in the ocean. If the pool where the Sim is snorkeling isn't spacious enough, the action will automatically be canceled.