The 75 Largest Underwater Species, Ranked by Average Size

Written By: Frank Bongiorno

With so many fish in the sea, which is the largest? Well the largest animal in the ocean isn't a fish at all but a whale. The blue whale is not only the biggest animal in the ocean, but it's also the biggest animal in the world. It's comparable in size to two school buses! What other giant sea creatures lurk under the surface of the water? Take a deep dive into this illustrated chart from Staten Island Yacht Sales that compares the average weight and length of the 75 largest underwater species alive today.

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What Is the Largest Underwater Species?

The largest underwater species is the blue whale, which weighs 242,500 pounds on average and has a length of 79 feet. While these are the average weight and length for the species, much larger ones have been spotted from whale-watching boats. The biggest whale ever recorded was more than 110 feet long, and the heaviest one on record weighed an unbelievable 418,878 pounds! Nearly all of the top ten largest are whale species, with the exception of the largest shark in the world, the whale shark, in tenth place.

The 10 Largest Underwater Species

1. Blue Whale: 242,500 pounds, 79 feet
2. Right Whale: 132,300 pounds, 51 feet
3. Fin Whale: 125,700 pounds, 64 feet
4. Bowhead Whale: 120,200 pounds, 49 feet
5. Sperm Whale: 68,900 pounds, 44 feet
6. Humpback Whale: 63,900 pounds, 44 feet
7. Sei Whale: 49,600 pounds, 49 feet
8. Gray Whale: 43,000 pounds, 44 feet
9. Bryde's Whale: 42,000 pounds, 44 feet
10. Whale Shark: 41,000 pounds, 48 feet

What Is the Largest Fish Species?

The largest fish species is the whale shark, which weighs 41,000 pounds and reaches an average length of 48 feet. Although it is the a member of the shark family, the whale shark's temperament and diet of plankton and fish eggs are much more similar to those of whales. The largest shark species are so docile that people are able to safely swim and dive with them.

The 10 Largest Fish Species

1. Whale Shark: 41,000 pounds, 48 feet
2. Basking Shark: 10,200 pounds, 26 feet
3. Sharptail Mola: 4,000 pounds, 9.8 feet
4. Hoodwinker Sunfish: 4,000 pounds, 7.9 feet
5. Megamouth Shark: 2,600 pounds, 18 feet
6. Greenland Shark: 2,200 pounds, 21 feet
7. Kaluga: 2,200 pounds, 18.6 feet
8. Ocean Sunfish: 2,200 pounds, 10 feet
9. Great White Shark: 2,000 pounds, 15 feet
10. Tiger Shark: 1,125 pounds, 12.5 feet

What Is the Largest Cephalopod Species?

What's bigger: the colossal squid or giant squid? The largest cephalopod species is the colossal squid, which weighs half a ton and reaches an average length of 32 feet. But how big is a giant squid? The giant squid weighs half as much, at 470 pounds, though its long tentacles give it a longer length of 38 feet.
The two other largest cephalopods in the sea found themselves at the bottom of the list of the largest underwater species. The seven-arm octopus, with an average weight of 133 pounds, just barely beat out the giant Pacific octopus, with a weight of 110 pounds, although the giant Pacific octopus is longer, with a length of 16 feet from leg to leg compared to 9.5 feet.