I Wonder What are some underwater endangered species? Amelia N. There are a lot of endangered species that live underwater. There are about 3,079 endangered species. But how many of those species live underwater? A lot. One underwater endangered species is a Blue Whale. They can get up to be 98 feet in length, and weigh as much as 170 tonnes or more. Because of their size, they really have no natural predator. Their main predators are humans. That’s it. Blue Whales are mostly endangered, because of whaling. But another reason, is because of other animals in the ocean. A lot of animals in the ocean can injure a whale, but almost never can kill in a fight. Also, they can be injured after colliding with an ocean vessel, or fishing gear, and sometimes even fatally. The Hawaiian Monk Seal can grow up to be six feet in length, and 600 pounds. They have a grey coat, with a white belly. Their predators are Tiger Sharks, and Galapagos. Besides that, another threat is male aggression. Males mob a female, which has been decreasing the female Hawaiian Monk Seal population. The Rainbow Parrotfish’s scientific name is Scarus Guacamaia. They are a species inside the Scaridae family. They can be fund int he Western Atlantic Ocean, from Florida, Bermuda, and the Bahamas from Argentina. It is a very rare fish, but more common in Bermuda. The Green Sea Turtle is also known as the Green Turtle. Only humans and large sharks are predators of the Green Sea Turtle. Although hatchlings have more predators because they are smaller. It is illegal to collect, kill, or harm them, but they can often get caught in fishing nets. The Stellar Sea Lion is also known as the Northern Sea Lion. They are a threatened species of Sea Lion in the Northern Pacific. The population was estimated to have decreased by 70-80% since the 1970s. They are listed as endangered in Alaska, Canada, California, North Pacific Ocean, Oregon, Washington, and Russia.