Refers to a person who dives, typically in a professional or occupational context such as underwater construction, salvage, or pearl diving. Not the most common word for a recreational diver (ダイバー is more typical).
The diver is inspecting the cable on the seabed.
When he was young, he worked as a pearl diver.
Compound of 潜水 (diving, underwater) and 夫 (man, worker). The exact historical derivation is uncertain, but the spelling is conventionally associated with a male occupational diver.