How deep can dolphins dive?

The deepest dive ever recorded for a bottlenose dolphin was a 300 meters (990 feet). This was accomplished by Tuffy, a dolphin trained by the US Navy. Most likely dolphins do not dive very deep, though. Many bottlenose dolphins live in fairly shallow water. In the Sarasota Bay area, the dolphins spend a considarable time in waters that are less than 2 meters (7 feet) deep.

Other whale and dolphin species are able to dive to much greater depths even. The pilot whale (Globicephala melaena) can dive to at least 600 meters (2000 feet) and a sperm whale (Physeter macrocephalus) has been found entangled in a cable at more that 900 meters (500 fathoms) depth. Recent studies on the behavior of belugas (Delphinapterus leucas) has revealed that they regulary dive to depths of 800 meters. The deepest dive recorded of a beluga was to 1250 meters.

F.G. Wood (1993)
Marine mammals and man.
R.B. Luce, Inc., Washington.
E.J. Slijper (1979)
Whales, 2nd edition.
Cornell University Press, Ithaca, NY.
(Revised re-issue of the 1958 publication: Walvissen, D.B. Centen, Amsterdam)
R.S. Wells, A.B. Irvine & M.D. Scott (1980)
The social ecology of inshore odontocetes.
In: L.M. Herman (ed.)
Cetacean Behavior. Mechanisms & functions, pp. 263-317.
John Wiley & Sons, New York
A.R. Martin (1996)
Using satellite telemetry to aid the conservation and wise management of beluga (Delphinapterus leucas) populations subject to hunting.
Paper presented at the 10th Annual Conference of the European Cetacean Society, March 11-13, 1996, Lisbon, Portugal.