Basking Sharks in UK Waters: Gentle Giants Return This Spring

Every spring, as the water around the UK begins to warm and the first plankton blooms colour the coast, one of the ocean's true giants returns to British waters. The basking shark, the second largest fish in the world, spends its summers cruising slowly along the surface off Cornwall, the Isle of Man, and the west coast of Scotland, mouth wide open, filtering huge volumes of seawater for the tiny plankton it feeds on. For a diving community based inland in Reading, the return of the basking shark each Easter is a genuine seasonal marker, a sign that the UK diving season is properly underway and that some of the country's most extraordinary wildlife encounters are once again within reach.

A Giant That Poses No Threat

Basking sharks can grow to over eight metres, making them second in size only to the whale shark, yet they are entirely harmless to divers and snorkellers. Their name comes from their habit of appearing to bask at the surface, drifting slowly with their enormous mouths agape, but what looks like lazy sunbathing is actually intense feeding behaviour. A basking shark can filter more than a thousand tonnes of water an hour through its gill rakers, straining out zooplankton, fish eggs, and tiny crustaceans in the process.

Despite their size, basking sharks are gentle, curious animals with small teeth used for nothing more than gripping soft food, not for hunting. Encounters usually involve slipping quietly into the water ahead of a surfacing shark and watching it glide past, often within a few metres, completely unbothered by a respectful observer. It is one of the most humbling wildlife experiences UK waters can offer, and it requires no tropical flight to reach.

Why Basking Sharks Need Our Attention

Basking sharks were hunted commercially around the UK well into the twentieth century, targeted for their liver oil, and populations have been slow to recover. They are now protected under UK law and listed as endangered on the IUCN Red List, but they remain vulnerable to entanglement in fishing gear, boat strikes, and the general decline in plankton productivity linked to changing sea temperatures. Because they reproduce slowly, with females thought to give birth to only a handful of pups every few years, any additional pressure on the population has an outsized effect.

Their slow-moving, surface-feeding habits also make them particularly exposed to collisions with boats, which is why responsible skippers and dive operators follow strict codes of conduct around approach distances and speed when a shark is sighted. Divers have a role to play here too, reporting sightings to organisations that track basking shark movements and never crowding or chasing an animal that is simply trying to feed.

How Sightings Help Science

Basking shark research relies heavily on citizen science. Photographs of dorsal fin shape and scarring allow researchers to identify individual sharks and track their movements between sightings, sometimes years apart. Divers and boat users who log what they see, including location, time, and rough size, contribute directly to a growing picture of how these animals use UK waters and where the most important feeding grounds actually are.

Diving Responsibly Around a Filter Feeder

Getting in the water with a basking shark comes with a set of unwritten rules that any competent skipper or guide will brief before entry. Approaches are made from the side, never head on and never from directly behind, entry is quiet and without splashing, and divers keep a respectful distance rather than finning hard to close the gap. A shark that feels harassed will simply dive and move on, ending the encounter for everyone in the water, so patience and a calm approach are rewarded far more often than an eager chase.

Visibility in the areas where basking sharks feed is often better than divers expect from UK waters, particularly on a settled day with good plankton density, though ironically it is the plankton itself that limits horizontal visibility even as it feeds the shark. Water temperature in April and May is still bracing, so a well-fitted wetsuit or drysuit is essential, and anyone planning a basking shark trip should be comfortable in open water with some surface current, since much of the encounter happens at or near the surface rather than on a wreck or reef.

What Divers Can Do Beyond the Dive

Protecting basking sharks does not stop at good in-water etiquette. Supporting marine protected areas that cover known feeding grounds, choosing operators who follow recognised codes of conduct, and simply talking about these animals to other divers all help build the case for stronger protections. Understanding the wider pressures on UK marine life, from bycatch to warming seas, is something our Conservation Academy covers in real depth, moving beyond a single species to look at how UK divers can genuinely contribute to healthier seas.

For divers who want to go further, specialty courses built around marine identification and survey techniques teach the skills used in real citizen science projects, turning a normal dive into a small but genuine contribution to ongoing research. It is a satisfying way to combine a passion for diving with a tangible sense of purpose beneath the surface.

Planning Your Own Basking Shark Encounter

Basking shark season typically runs from May through to July, peaking as plankton blooms build through late spring, which makes an Easter season kickoff the perfect time to start planning. Trips are weather dependent and often booked at short notice once sightings begin, so flexibility matters more than a fixed date. A good level of open water confidence, comfortable buoyancy control, and a properly fitted exposure suit for UK spring temperatures will make the day far more enjoyable than trying to cope with cold or poor trim while a shark cruises past.

If you are relatively new to UK diving conditions, building confidence through structured training first is time well spent before tackling a surface encounter with an eight metre animal, however docile. Our team regularly advises divers on the right preparation for seasonal wildlife trips, and getting your kit and skills sorted in the weeks before the season really gets going means you can focus entirely on the shark when the moment finally arrives.

Frequently Asked Questions

Are basking sharks dangerous to divers?

No. They feed exclusively on plankton and have no interest in divers beyond mild curiosity. The main consideration is giving them space so they do not feel pressured to dive away.

Do I need advanced qualifications to see one?

Most encounters happen snorkelling or diving from a boat in open water, so solid buoyancy, comfort in current, and confidence with UK conditions matter more than a specific certification level, though experience helps you get the most from a short window in the water.

When is the best time to see basking sharks in the UK?

Late spring through midsummer is the reliable window, with sightings often peaking in May and June as plankton blooms intensify along the west coast.

Fancy building the skills and confidence for a UK wildlife encounter like this? Browse our courses or learn more about how we approach marine life through the Conservation Academy. Get in touch on +44 (0) 118 9761 729 or visit us at Bellman Court, Great Knollys Street, Reading, RG1 7HN.