Our citizen science programme allows us to utilise both opportunistic and effort based data to identify individuals and better understand their behaviour, movement, prey species and breeding sites. This data is used to build knowledge, seek better protection for our marine environment and ultimately safeguard Sussex marine mammals.

We Believe In Citizens

Research into marine mammals off the coast of Sussex has been minimal. With the busy shipping traffic, commercial fishery and high recreational use, it was presumed that this would be an area with low marine mammal activity. However, anecdotal and historical evidence indicated that this is not the case and we are beginning to learn more about these animals thanks to citizen science. 

We are looking for motivated individuals or groups to get involved with our Land-Watch surveys and help us to create a network of marine mammal spotters, collecting much-needed data all along the Sussex coastline. 

Our training dates are weather dependent so please keep an eye on our social media channels, or sign up for news from the Sussex Dolphin Project to hear about new dates. 


These are the main marine mammal species that we see off the Sussex coast. 

Bottlenose dolphins are the most common species, but if you’re lucky you may spot the acrobatic common, the deep water white-beaked or the elusive harbour porpoise!

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Bottlenose Dolphin © Marina Lewis-King

Bottlenose Dolphin

Adults can grow to 1.9-3.9m long. They have a large grey body, a pale grey or pinkish belly and a tall sickle shaped dorsal fin. Bottlenose Dolphins are commonly seen in groups of 2-15 individuals, however large groups and single dolphins are not uncommon. These animals are playful and curious, and are often seen bow riding the waves of boats and leaping clear out of the water.


Common Dolphins © Dylan Walker

Common Dolphin

Common dolphins have a characteristic figure of 8 pattern on their flanks which is tawny/yellow, brown, grey and black. They have a white belly and a sickle shaped dorsal fin. They are between 1.7-2.5m long. Common dolphins are a highly active species. They are fast swimmers and regularly ride the bow waves of boats.


White-beaked Dolphin © Dylan Walker

White-beaked Dolphin

A large, sturdy dolphin that can grow to 3m in length. They have distinctive pale grey-white flashes along the flanks and a pale grey patch behind the dorsal fin known as a saddle patch. They have a dark grey back, tail and pectoral fins. Their dorsal fin is tall, and sickle shaped and their beak is usually although not always pale grey or white. White-beaked dolphins are fast swimmers, acrobatic and they often ride the bow waves of boats. They are most often spotted offshore in groups of between 5-20 individuals but can form larger groups.

Harbour Porpoise © Thea Taylor

Harbour Porpoise

Harbour Porpoises can grow to between 1.4 to 1.9m in length. They have a stocky body, a small rounded head that lacks a beak and a triangular dorsal fin that has a blunt tip. The body is a dark grey which lightens on the flanks and their underside to light grey or white. They are most often seen in groups of 2-5 individuals, however they are also sighted alone. Harbour porpoises are known to be elusive and will rarely approach boats. Harbour Porpoises generally travel quite slowly and tend to be sighted in relatively inshore waters and coastal regions.

Harbour Seal © Oscar Cardinal

Harbour Seal

Harbour (or Common) Seals are regularly seen off the Sussex coastline. They can grow to between 1m-1.8m. The most distinguishing feature is that they have cat-like facial features. Their colouration ranges from light tan to brown, and with some darker speckles on their body. Harbour seals are mainly found in the coastal waters of the continental shelf and slope, and also commonly found in bays, rivers, estuaries and intertidal areas.

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Grey Seal © Robin Taylor

Grey Seal

Grey Seals are less commonly seen off the Sussex coastline, but are still often sighted. The larger of the 2 species of seals found in the UK, they can grow to between 1.6m-2.8m. They can be distinguished from Harbour Seals by their dog-like facial features, and long roman nose. Their colouration ranges from light grey to dark grey, with darker speckles on their body. Grey Seals are often found on rocky shores, and can form large colonies on sand dunes.


Dolphins and porpoises display a range of interesting and exciting behaviours:

  • Bow/wake riding: Dolphins often swim in the pressure wave formed ahead of boats and the wake behind them, scientists still don’t know the reason behind this, the only explanation is that they do it for fun!

  • Slow travel: Dolphins maintain a steady speed by only raising the upper parts of their body as they surface.

  • Porpoising or running: Dolphins can travel at a high speed by leaping clear of the water.

  • Chorus lines: Pods of dolphins often change direction as a unit and can swim in a line formation.

Remember: Dolphins, Porpoises, and Seals are wild animals. If you are lucky enough to encounter them at sea, keep your distance and be respectful.

Report your Sightings

If you see any Dolphins or Seals, please submit your sighting using the button above or send the details via our social media profiles. The information we’d like to receive is:

  • Species (Dolphin, Porpoise, or Seal)

  • Number of animals

  • Location (Coordinates or nearest landmark)

  • If there were any juveniles present.

  • Behaviour of the animals (swimming, jumping, interacting with boats, feeding, resting)

  • Time and date

Please do also share any photos and videos you have as well. All of this data will be added to our Public Sightings Database, so we can develop a better understanding of these charismatic animals in Sussex, as well as finding out more potential populations of Dolphins, Porpoises and Seals in the area.