It overwhelms your senses in the most welcome way. Land-based stresses are forgotten, and phones fall silent. There’s nothing else to do but scan the sea for a splash. The anticipation is totally absorbing and exhilarating. Every time, I feel like a child exploring and turning over stones. I think we all need a bit more of that feeling in our lives.

Pembrokeshire reaches out like an arm into the Celtic Sea. It’s the perfect access point for us to view large megafauna that follow the Gulf Stream to UK waters and then pass up through the deep waters of the St Georges Channel between Ireland and the UK. It’s rugged cliffs and offshore islands are some of the most important refuges for a number of our most iconic seabirds and seal colonies.

When, after many years spent travelling and diving around the world, I moved to Pembrokeshire, I was blown away by the amazing variety of wildlife on its doorstep. While cruising and diving it’s bottle green waters, I’ve spotted pilot whales, fin whales, minke whales, blue sharks, basking sharks, sunfish, bluefin tuna, seals and even the odd leatherback turtle. Our most common whale sightings are the minke whale. One of the smallest baleen whales, yet when in amongst the pods of dolphins they look huge! They’re known for their inquisitive nature. On one trip one individual stayed with us for half an hour, circling the boat. They’re most impressive when feeding. Flying into bait balls of shoaling fish, brought to the surface by tuna and dolphins.

Although not as deep as it’s evocative name would have you believe, at 100m depth the waters of the Celtic Deep offer the vertical range that suits some species of large sharks. Blue sharks are the most numerous – in fact they’re the most numerous and wide-ranging species of shark in the world. They’re also some of the most heavily fished. The individuals we see are generally mature females who migrate North to our waters from breeding grounds in the central/Eastern Atlantic. We commonly encounter groups of three and sometimes up to eight sharks at a time – blues are very curious sharks who will stick around and circle around to nuzzle and bump us to see what we are. As the water cools, they return South East to mate with males, most of which migrate East or South, some as far South as Brazil.

Early in the season, porbeagles are common. A stout, powerfully built shark that resembles a miniature great white in contrast to the slender serpentine blue shark. Often, they are the first to arrive at the boat once we’ve turned off the engine and become a floating platform. However, they are shy of interaction, so don’t stick around for too long once we enter the water. We’ve also seen thresher sharks breaching near the boat. It’s an impressive sight. Repeatedly leaping and showing off their long tails, which makes up at least half of their overall length. We’re yet to see one in the water – they’re renowned for being quite timid.

One shark we’re yet to see ourselves in these waters is the short-fin mako. Unfortunately, an 11-foot mako was caught by sport fishermen on one of the same days we were out there last year, so they are definitely around. Being in the water with these sharks is such a privilege. There are clear behavioural differences between species, but also between individuals of the same species. Blues are so inquisitive, they can spend all day in a holding pattern, gliding past each person in turn before inspecting the boat and anything else in the water. To simply observe these creatures, which have been honed by hundreds of millions of years of evolution, and to grace their realm is quite an extraordinary experience.

Last summer we encountered minke and fin whales on a regular basis, both travelling solo and working in a group to feed on bait balls. The sheer size of these whales and the co-operation between them, dolphins, tuna and birds to round up and then all feast from the bait balls was fascinating to watch. The fin whale is the second largest whale in the world (the blue whale pips it by 6m at the largest recorded 33m, versus the fin whale’s 27m). It is believed to be a year-round resident in UK waters and one of the largest recorded gatherings of fin whales in UK waters was in the Celtic Sea.

I grew up by the sea and spent as much time as I could in the water. I think the ocean has always been deep in my bones. I truly believe that we all need our wild space. Somewhere that makes us feel closer to nature, conjures a sense of wonder and puts life into perspective. The sea has always been that space for me. One of our main goals with our Celtic Deep expeditions is to get more people in these waters so that they can actually see amazing marine creatures in their natural realm, and so raise awareness of the incredible wildlife that can be found right here in the UK.  Despite spending most of my childhood in British waters, I learned little about the diversity that lay beneath the surface until later in my life.