Seals, dolphins and even a small crocodile were discovered during a survey of the UK's waterways.
The British Waterways study had the help of hundreds of visitors to its canal and river network.
And while mallards, swans, moorhens, herons and coots are identified as the top five most common species to the waterways, a number of extraordinary birds and animals were seen, such as porpoises and ospreys.
More than 3,700 sightings were recorded of 60 different species, including some of the UK's rarest wildlife, such as endangered water voles, otters and the infrequently seen kingfisher.
However a significant number of people also saw the non-native mink, providing an indication of their prevalence on the waterways.
The information gathered from hundreds of participants will be used by British Waterways, which cares for 2,000 miles of canals and rivers, to help manage and protect the rich array of wildlife in and around the waterways.
It will be incorporated into the national species database, which records biodiversity on the inland waterways.
One in eight people surveyed reported the presence of mallards and swans while one in 20 people observed kingfishers and water voles.
Sightings of non-native species also included terrapins, and Chinese mitten crabs. Of considerable concern are the mink observations.
Jonathan Brickland, British Waterways' national ecologist, said: "Some amazing wildlife has been spotted on our waterways and we want to encourage more people to visit our canals and rivers and enjoy the rich variety of animals and plants.
"Whilst we are surprised to find a crocodile and osprey listed we are not ruling these out until further investigations take place."