Perth, Australia - Cindy Joli was able to experience something that many people can only dream of when she swam with a pod of dolphins. The marine biologist noticed something cruel when later reviewing her video, however.

Joli was snorkeling off the coast of the Australian city of Perth when she suddenly encountered several dolphins in the sea.

Completely overwhelmed, the marine biologist immediately pulled out a camera and captured the magical moment.

When she later reviewed her footage, though, she noticed a detail that she had missed while diving in the murky seawater: one of the animals had been severely injured on its tail fin.

Dogs These Golden Retrievers are the world's best babysitters in heart-melting viral video!

Joli writes that a fishing line had become entangled in the porpoise's fin and cut deep into the flesh of the propulsive organ.

The injury may have already caused an infection, which could lead to the loss of the tail fin, according to Yahoo News.

Without the tail fin, the dolphin is severely restricted in its locomotion and can only swim to the surface to catch its breath or escape from predators – although with some difficulty.

"Unfortunately this is a very common occurrence seen along our coast. Not just dolphins but a variety of other wildlife that I have personally seen way too many times," the scientist wrote on Instagram.

Joli would have helped the dolphin immediately and put it out of its misery if she had spotted the fishing line during the dive.

Due to poor visibility, however, she only noticed the injured fin afterward.

Cats This adorable lounging kitty cat is ultimate cozy movie night goals!

This comes as a bitter blow for the devoted conservationist.

"Saddens me," she said.

"People should not cut fishing lines but [instead] reel them in and of course, pick up rubbish whenever it's seen on beaches and in the sea, to help reduce the negative impact on our local wildlife," Joli said in an interview with Yahoo News.