Diver

Part of speech: noun (n.)

1. One who, or that which, dives. Divers and fishers for pearls. Woodward.

2. Fig.: One who goes deeply into a subject, study, or business. "A diver into causes." Sir H. Wotton.

3. Any bird of certain genera, as Urinator (formerly Colymbus), or the allied genus Colymbus, or Podiceps, remarkable for their agility in diving.