The open ocean rewards bodies built for speed, and the quickest swimmers include fish, mammals, a reptile and even a mollusc. Some figures come from tagged animals while others are disputed estimates, so each number is best read as a top burst rather than a cruising pace. Here are twelve of the fastest, starting with the record-setting sailfish.
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1. Sailfish: Fastest Burst Ever Tagged
Scientists in 2015 were amazed when a tagged sailfish accelerated at 1.79 g, a burst equal to 78 mph, as noted in Discover Wildlife’s ocean ranking. The figure came from one tagged fish and was derived from its acceleration, which explains why it tops the list.
That makes the sailfish the benchmark for ocean speed, with the caveat that the number describes a brief sprint by a single animal. Sustained swimming speeds for the species are lower, and a short burst is a different thing from a cruising pace.
2. Yellowfin tuna: Built to Cruise Fast
The yellowfin tuna is listed at 47 mph, or 76 km/h, in the Fastest animals list on Wikipedia. Its tail beats so quickly that it can cause cavitation, a buildup of vapour bubbles that actually slows the fish down at the very top of its range.
That quirk means the tuna is bumping against a physical limit rather than a lack of muscle. A torpedo-shaped body and crescent tail let it hold a strong pace across open water, which helps explain why the species ranges so widely through tropical and subtropical seas around the globe.
3. Swordfish: Built Like A Blade
The swordfish owes its place to a streamlined body that lets it reach speeds of up to 62 mph, according to Discover Wildlife’s list of the fastest swimmers in the ocean.
Its long bill and tapered shape are the visible clues to that performance. As with other entries here, 62 mph describes a peak, not what a swordfish does while patrolling open water, so the number marks capability rather than daily habit.
4. Wahoo: Full Pelt Through Open Water
The wahoo can reach up to 48 mph at full pelt, a speed Discover Wildlife reports in its roundup of the ocean’s fastest swimmers.
That puts the slender, torpedo-shaped fish well ahead of most sharks and mammals on this list. It is a reminder that some of the sea’s quickest predators are not famous names, and the wahoo’s reputation among anglers rests on exactly this kind of raw speed, which suits a fish of its slim build.
5. Shortfin mako shark: Sprinter Among Sharks
The shortfin mako shark can accelerate up to 46 mph, though it usually swims around 31 mph, according to Discover Wildlife’s ranking.
The gap between the two numbers is the useful detail. Even the usual pace is brisk for a shark, while the higher figure shows what a mako can summon when chasing prey. It is widely regarded as the speed champion among sharks, and a standout in any ranking of the ocean’s fast fish.
6. Atlantic bluefin tuna: Warm-Blooded Torpedo
Bluefin tuna can hit speeds up to 43 miles per hour, the Ocean Conservancy states in a post comparing ocean animals with Olympic swimmer Michael Phelps.
That comparison is the point: the fastest human swimmers are far slower than a tuna. The Atlantic bluefin is a large, muscular fish whose build is made for covering long distances quickly, so the burst figure is only part of its overall athletic profile as one of the ocean’s great travelers.
7. Orca: Fastest Marine Mammal
The orca is the fastest marine mammal on the list, with a top speed of 35 mph, or 56 km/h, as given in the Fastest animals entry on Wikipedia.
That is quick for an animal of its size, and it helps explain how the largest member of the dolphin family can hunt fast prey. The figure is a top speed, so the orca’s everyday travel is much slower than this peak.
8. Fin whale: A Giant That Can Sprint
The fin whale can burst to 25 to 29 mph, or 40 to 46 km/h, with a satellite- or GPS-measured sustained maximum of about 25 mph, according to the Fastest animals entry on Wikipedia.
Few animals of such enormous size move this fast. The two figures show the difference between a short burst and a speed that was measured over time, and the fin whale is often described as one of the swiftest of the great whales.
9. California sea lion: Speed Beneath The Surface
The California sea lion can swim up to 25 miles per hour underwater, the Ocean Conservancy notes in its list of animals faster than Michael Phelps.
The qualifier underwater matters, because the sea lion is agile in the water in a way it never is on land. That agility makes it a familiar sight around harbors and coasts, where its quick turns and bursts of speed are easy to notice.
10. Common octopus: Jet-Propelled Mollusc
The common octopus can jet to speeds up to 25 miles per hour, the Ocean Conservancy says in its comparison of ocean animals with a champion swimmer.
Jetting is a defensive move, achieved by forcing water out of the body, and it is quite different from the steady swimming of fish. The octopus is the only invertebrate on this list, which makes its place among the speedsters all the more notable.
11. Leatherback sea turtle: Fastest Reptile Afloat
The leatherback sea turtle is the fastest reptile in the water at 21.92 mph, or 35.28 km/h, according to the Fastest animals entry on Wikipedia.
It is the only reptile on the list, and its speed fits the largest of the sea turtles, a species known for long ocean journeys across wide stretches of sea. The number is a top speed, not a typical one, but it shows that a turtle can outpace many swimmers.
12. Bottlenose dolphin: Familiar And Fast
The bottlenose dolphin can swim at speeds over 18 miles per hour, according to the Ocean Conservancy’s list of animals that are faster than Michael Phelps.
It ends the list because it is the slowest of the twelve, yet it is still far quicker than any human swimmer. The dolphin’s blend of speed, agility and endurance is a large part of why it is among the best-known marine mammals in the world.
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