For swimming, there's the Buoyancy Control Specialty (SP), and for deep diving, the Deep Diving SP is crucial as it's dangerous without the proper knowledge.
When diving from a boat, you'll be in open water, so there's much to learn, such as dealing with currents and the precautions for entering and exiting the water from a boat!
Specialty courses are designed to refine your skills and help you grow as a diver.
For details on available courses, please visit the dedicated page.