What Divers Should Know About Ocean Sunfish

Appearing like a colossal fish head with fins but no tail, the Ocean sunfish (Mola mola) immediately stands out underwater. Its main body is flattened laterally, giving it a distinctive truncated shape where a caudal fin would typically be, replaced by a rounded clavus. These magnificent creatures are among the largest bony fish globally. Adults frequently weigh between 247 and 1,000 kg (545 and 2,205 lb), with records of individuals reaching 3.3 m (10 ft 10 in) in length and weighing an astounding 2,300 kg (5,100 lb). Their elongated dorsal and anal fins can make them as tall as they are long, reaching heights of 3.3 m (10 ft 10 in).

Native to the temperate and tropical waters of every ocean, these solitary giants are typically observed alone, though occasionally in pairs. Despite earlier beliefs of being passive drifters, Mola mola are active swimmers, capable of covering significant distances. While they often hunt at depths greater than 200 m (660 ft), sunfish are known to ascend to the surface and bask on their sides, a behavior believed to "thermally recharge" after deep, cold dives. This surface activity offers a unique opportunity to witness one of the ocean's most unusual inhabitants in its natural environment.