The new app hopes to build a country-wide picture of the marine mammals so conservationists can understand more about their life.
Building a country-wide picture of Grey seals around Britain's coastline - that's the aim of the Seal Spotter Smartphone app.
The charity The Seal Project, together with researches at Plymouth University, are asking citizen scientists across the UK to help track the mammals.
"It helps us understand more about the life of the Grey seals around our coast," said Duncan Kenny, from The Seal Project, "because we have about 40 per cent of the global population of Grey seals in the UK, around the UK waters. So, as a vulnerable species, we need to kind of understand more about them, so we can better protect them."
Conservationist will be able to find out if seals are alone or in groups if they've been entangled in plastics or showing signs of injury and whether they're feeding, resting or fighting.
Zuzanna Helska is a resident in Brixham, Devon and an app user said, "It's very important research. These are transient mammals, so knowing where they hang out and where they go from here is very, very interesting, and helps us understand their life."
In the early 20th century Grey seal numbers dropped to just 500 according to The Wildlife Trusts.
But now there are around 120,000.
"It will enable us to learn so much more about them as a species and protect them better," said Sarah Greenslade, co-founder of The Seal Project. "Obviously, all the identifications, we can see how far they can travel, and different locations are matching up rescued seals all over the place. So, we can learn an awful lot."