Some people say a big, hairy creature called Bigfoot lives in forests in the northwest of North America. It is said to walk on two feet, to be taller than a grown-up and to be covered in long, dark hair. The word Sasquatch comes from a Salish word that means "wild men." Footprints said to be Bigfoot's are very large, up to about 20 to 24 inches long. No body or bones of Bigfoot have ever been found.

In 1958 a worker in California found huge footprints near a road being built. The prints were nearly 16 inches long. A California newspaper, the Humboldt Times, started calling the maker of the footprints "Bigfoot." In 2002, after Ray Wallace died, his family said he had made the 1958 footprints with carved wooden feet. The most famous film said to show Bigfoot was shot in 1967 near Bluff Creek, California. No one has verified it as showing an unknown animal.

Scientists tested hairs said to come from Bigfoot and similar creatures. Almost all came from known animals such as bears, horses, cows, raccoons and sheep. Some scientists think people who report Bigfoot may be seeing bears, which can stand up on two legs.

The saola, a large forest animal, was found by scientists in 1992 in Vietnam, near the Laos border. It was the first large mammal new to science in more than 50 years. The giant squid was once known only from sea-monster stories, but it is a living animal of the deep ocean. Scientists use camera traps, which are cameras with motion sensors that take pictures by themselves, to see shy animals.

Loch Ness is a very big lake in Scotland. It holds more water than any other lake in Britain. It is about 23 miles long and about 800 feet deep. Some people believe a big animal lives there. They call it Nessie. The modern Nessie story began in 1933, after a new road along Loch Ness gave people a clear view of the water. People who report Nessie often describe a long neck, or humps that stick up out of the water.

In 1934 a photo seemed to show a long neck rising out of Loch Ness. It was called the Surgeon's Photograph. It was shown to be a hoax in 1994, about sixty years after it was taken. A famous photo of Nessie was a trick. The "monster" was a model head on a toy submarine. In 1933 footprints found at Loch Ness were sent to the Natural History Museum in London. Experts there said they were made with a hippo-foot umbrella stand or ashtray.

Many sightings at Loch Ness could be waves, boat wakes, logs, birds, seals, otters or swimming deer. Most photos said to show Nessie turned out to be fakes, or to show other animals or objects. A plesiosaur was a sea reptile that died out about 65 million years ago. Some people thought Nessie might be one. Scientists and TV teams swept Loch Ness with sonar, which uses sound to find things under water. Searches in 1987 and 2003 found no monster.

Animals and plants leave bits of DNA in the water around them, from shed cells and waste. Scientists can collect it and read it. In 2018 scientists from New Zealand took more than 250 water samples from Loch Ness to find out what lives there. They found no plesiosaur DNA, and no sturgeon either. Eel DNA turned up in nearly every sample, so there are a lot of eels there. You may have heard that the survey proved Nessie is a giant eel. In fact, eel DNA does not tell how big the eels are, so the 2018 team could not rule out giant eels or say that they exist.

Words to know

• hoax: a trick
• sonar: sound finder
• DNA: body code
• plesiosaur: sea reptile
• verified: confirmed