However, they are still secretive animals, and getting a glimpse of these aquatic characters can still be tricky. We check out some of the UK's otter hotspots, and the telltale signs to look out for.
Otters are at their most active at night, and will often emerge from their holts at dusk and fish until dawn, and that means an early start is required if you are to catch sight of one. However, some freshwater otters have taken to living by the coast, and it is often possible to see them during the day as they rely on the tide to bring in their meals.
Since holts are underground, usually with an entrance low down on the banks of a river or lake, and will probably be screened by vegetation, your best chance of seeing an otter is when it is out and about. Look for droppings, or spraints, which are often deposited on prominent rocks or mounds of grass, and the prints of their webbed feet. Otters often take a regular route when they are on land, so keep an eye open for pathways.
Cricklepit Mill, Devon
A surprisingly sight regularly at this urban site close to Exeter city centre, with otters often turning up to visit the Mill. Visitors can watch footage of those that have dropped in, as well as see birds such as kingfisher, little egret and dipper.
Aughton Woods, Lancashire
The River Lune is a well-known otter hotspot, and if you're a casual wildlife watcher, Aughton Woods is the ideal place to start, as you can enjoy sandpipers and oystercatchers along the way, and the ancient woodland itself is a pleasure to behold.
Gilfach Farm, Radnorshire
Otters are seen at all times of the year and all times of the day in this stunning Welsh setting, but if you can brave the cold, try visiting from October to December, when the otters turn up at the waterfalls to take advantage of the leaping salmon.
Winnall Moors, Hampshire
A wetland haven for many of Britain's native species, otters pass through the Winnall Moors reserve near Winchester on a regular basis, and the paths, boardwalks and bridges over the River Itchen are a great place to stop and spot their beady eyes peaking out of the water.
In 2012, a mother and her two cubs were seen on a number of occasions at Staveley, close to Broughbridge, and it's a great site for spotting otters. This beautiful setting is also home to more than 230 plant species and birds including the rare short-eared owl and jack snipe.
Ditchford Lakes and Meadows, Northamptonshire
The gravel pits, grassland and scrub at Ditchford Lakes is the ideal site for breeding and wintering birds, and otters are frequent visitors. Even if you don't catch sight of the real thing, you'll have fun searching for their distinctive footprints in the wet mud.
Ranworth Broad and Barton Broad, Norfolk
The Norfolk broads are perfect for otters, and are often seen taking advantage of the water and marshes. Ranworth Broad is a site of national importance for wildlife, with large numbers of wildfowl making their home there in the winter, while Barton Broad regularly plays host to not just otter, but bittern and marsh harriers.
Falls of Clyde, Lanarkshire
A reserve stretching along the Clyde Gorge, otter, peregrine, badgers and bats are all to be found here, and the views of the falls are simply spectacular. Alternatively, for a good chance of seeing otter during daylight hours, head to the west coast of Scotland. Spey Bay and the Hebrides are particularly popular with otter who take advantage of the sea's bounty, and there's always the chance to see dolphins and seals too.
Have you seen otters in your local area? Let us know below...