Beachgoers at Wellington's Lyall Bay were urged to evacuate the water today after a "large" shark was spotted swimming in the area.

A Lyall Bay lifeguard told 1News the shark appeared around 12.50pm - which is when they asked swimmers to leave the water.

The lifeguard said a group of them took an inflatable boat out to observe the shark and described it as being one to two meters long.

While they managed to determine the size, the species of shark remains unknown.

"Due to our safety protocols, we weren’t able to get too close to the shark, so we couldn’t determine what species it was," the lifeguard said.

While movies depict a shark's arrival at beaches as a scene of panic, the lifeguard said everyone remained calm.

"They were all pretty happy to get out of the water; no one was reluctant, given the situation.

"Everyone stayed pretty calm and listened to what we had to say.

"It's their domain, so we need to acknowledge that."

A surfer told 1News that he was in the water when the shark showed up and that while it was big, he didn't feel too worried about it.

"I was sitting in the water, and I saw a dorsal fin; it went in the water, and I saw a flick of the tail and was like, alright, I'm getting out.

"I wasn't too worried or anything," he said.

Another local said she knew about the shark but was still keen to take a dip.

"I have my togs on," she said.

"It's probably pretty far out, so I wouldn't worry about it too much."

The beach was closed for over an hour before the shark swam off, and humans could return to the water around 2.15pm.

According to DOC, around 66 different species of sharks are found in New Zealand water - ranging from the 27-centimetre pygmy sharks to great whites and even 12-meter-long whale sharks.