A marlin is a fish from the family Istiophoridae (includes about 10 species). It has an elongated body, a spear-like snout or bill, and a long, rigid dorsal fin which extends forward to form a crest. Its common name is thought to derive from its resemblance to a sailor's marlinspike. Even more so than their close relatives, the scombrids, marlins are fast swimmers, reaching speeds of about 80 km/h (50 mph).
The larger species include the Atlantic blue marlin, Makaira nigricans, which can reach 5 m (16.4 ft) in length and 818 kg (1,803 lb) in weight and the black marlin, Istiompax indica, which can reach in excess of 5 m (16.4 ft) in length and 670 kg (1,480 lb) in weight. They are popular sporting fish in tropical areas.
In the Nobel Prize-winning author Ernest Hemingway's 1952 novel The Old Man and the Sea, the central character of the work is an aged Cuban fisherman who, after 84 days without success on the water, heads out to sea to break his run of bad luck. On the 85th day, Santiago, the old fisherman, hooks a resolute marlin; what follows is a great struggle between man, sea creature, and the elements.