Kneeling in sand rippled by the ocean current, I spread out my arms as a school of yellowtail snappers dart by. Although I’m only three metres under water, I keep watch, looking up every so often to see sun striking the pale blue water.

To a beginner diver, the colour blue is home. Azure, cerulean, turquoise. The lighter the shade, the closer you are to the surface. Indigo and cobalt means you’re going deep.

Waiting, I dig the tips of my fins into the sand as if they will take root and ground me. Then as if floating on the waves a group of stingrays appear, their flat bodies spread wider than my outstretched arms. I hesitate under their shadow, their mouths churning above my head. But as their grey fins float over me, I realize how gentle they are. As they approach again, I lean back and run my hand along their underbellies, supple like soft leather. Their fins enclose my body like wings and an awe and wildness flows through me.

Grand Cayman Island is the only place in the world where you can get this close to stingrays. For a beginner the experience can be overwhelming, but for a diver of any level an intimate encounter with these large underwater creatures is a unique opportunity. I had snorkelled with seals and penguins and marine iguanas in the past, but this time I wanted to dive. I had never seen seven-tenths of our world. Until now I remained on the surface, peering down from docks and coral edges. I wanted to slip lower into the blue waters, nine to twenty metres down, and enter the deep reef.

Although you can snorkel with stingrays along the shallow sandbar where they feed, nothing comes close to diving with them. When you’re snorkeling, one deep breath gives you seconds in this world. Diving with stingrays down at three-and-a-half metres – touching them, being literally hugged by them – lets you live in their world.

Local fishermen initially attracted the ground-feeding Atlantic Southern stingrays by cleaning their catches in this protected sandbar off North Sound. Over the years, the creatures became accustomed to interacting with divers and snorkellers and in 1987 dive masters first started bringing groups to what has become known as Stingray City – a natural channel through the barrier reef where stingrays feed.

Yet the entire island of Grand Cayman is one big dive site. Within a quarter mile from shore, the 22- by 8-mile limestone island slopes to shallow areas of 20 to 35 feet and then drops into sheer walls. There are many operators that offer PADI Open Water Certification, which will eventually allow you to dive with a buddy and no additional professional supervision. The course generally runs over three to four days – on a week long trip this still gives you a few days of open water dives on Cayman’s walls, coral canyons and sand chutes.

Dive Tech, a dive center offering recreational tours and technical training, is located on the northwestern tip of Grand Cayman Island. Down a road that winds past small houses with the odd cow tied to a tree in the front yard and chickens scuttling across lawns, the center is far away from the tourist strip and offers a perfect setting to slip into the underwater world.

The PADI Certification class begins at 8:30 am so arrive a day beforehand for time to settle in. The course is demanding; theory classes start in the morning and by afternoon you’re doing a pool dive.

Before I can experience the phenomenal sights of the deep reef, I have to get the knack of breathing underwater. The first pool dive is the most unsettling. It’s uncomfortable and even scary when you first breathe through a regulator. It requires a deep, slow, long breath and feels as though your lungs can’t get the breath in fast enough. As underwater exercises start, you adjust to breathing quite soon.

The second day is even more nerve-wracking. I’m embarking on the first of two open water dives. The safe confines of the pool walls aren’t there to reassure me and all I see are shades of blue as I descend into the ocean. Although the instructor points to a lobster under a rock ledge, crabs lurking in crevices and sea fans waving in the ocean current, all I register is pale light blue above and the darker water below.

Underwater drills also take on a different form. I have to let my mask fill up with water before I try to clear it and pretend to run out of air to practice breathing with my buddy’s regulator. I can’t quickly pop to the pool surface if there’s a problem. We’re now 30 feet below the surface and would have to ascend slowly to decompress properly without damaging my lungs.

Even above water the conditions can be rough. Shore entries in the cove can be trickier than diving off a boat in open water – especially when there’s a strong current and waves pushing you close to the rocks. But once below the churning waves, the water is wonderfully calm.

By the third day of the class, I’ve grown used to my new environment. Three days worth of studying a 250-page book, plus classroom, pool and dive instruction have finally come together. By the time my certification test rolls around, much of the diving feels like second nature and the sensation of floating weightlessly makes me feel like an astronaut.

Since the risk of developing decompression sickness is high if you fly within 18 to 24 hours of diving, I can’t spend my last day underwater. Luckily, there is plenty to see above water too. At Queen Elizabeth II Botanic Park near Seven Mile Beach, you can wander among 40 acres of flora and fauna, including a chance to spot one of 40 rare Grand Cayman blue iguanas. The National Museum contains more than 2,000 items including a 14-foot handmade catboat, old coins, documents and rare natural history specimens. At the national historic site of Pedro St. James, the oldest house on the Caymans, you can step back in time in its shady garden.

I opt to spend a full day relaxing at the remote Rum Point on the east side of the island, where hammocks are strung near the water’s edge. After watching the sunset, I stroll to a beachfront restaurant for dinner.

If you still don’t have diving out of your system, you could head to the capital, George Town, and take the Atlantis Submarine down 100 feet to tour Grand Cayman’s underwater Marine Park. Or for a more unusual glimpse of the depths, and if you book far enough in advance, squeeze into Atlantis’ Deep Explorer, a three-person deep-sea research submarine that drops to 1,000 feet.

But no Cayman experience can come close to Stingray City. The experience is unique in the world and extremely moving. When the stingrays start swimming around me I'm so excited that I forget to take out the bits of frozen squid to feed them. I eventually hold a chunk flat in my hand as I’d been instructed and the stingrays come and gently take it from me. But then another ray, also hungry, grabs the skin on my forearm and as if I am a giant crustacean, starts sucking my skin in between his two raspy plates. I shove it away but like a rug suctioned to a vacuum cleaner, I have to apply some force before he budges.

By that time my left arm is blotched with red flecks of broken skin. Fear and vulnerability course through me. I want to bolt for the top but I know I must ascend slowly. So I sit in the shallow waters for a moment and when I don’t see blood pouring from my arm, and the pain subsides, I realize I have simply been given a stingray hickey. I open my arms once again and let them float over my body.

When we are ready to surface, I look once more at my arm, the bruise now turning purple. This time I don’t look up, but back at the rays. And I remember my two dives earlier where I saw a five-foot moray eel, olive against the rusty coral; silver tarpon twice the size of my arm swimming alongside me as if I were one of them; twin ruby spirals of the Christmas Tree Slug, retracting the moment I waved my hand over it.

Finally, I see colour.