Sinking into the waters of the Andaman Sea, part of the Indian Ocean to the south of Myanmar (Burma), I focused on the coral to my left rather than the impenetrable blackness on my right.
Divers call it "The Big Blue", but all I cared was that it wasn't hiding a big shark. I squinted hard at a nearby clown fish to calm myself down.
It worked. The loud, rhythmic rattle of my breathing, the sensation of weightlessness and the bewitching neon fish darting inches from my face helped to produce a kind of soothing alchemy that only ever occurs under water.
By the time my dive was up 50 minutes later, I was a ball of neoprene-clad bliss.
Research suggests that I am not alone in succumbing to the restorative powers of the ocean. A 2017 study by French institutions found that recreational diving could be more effective at reducing stress and boosting mental well-being than other sports.
The study concluded that the health benefits of diving for leisure include "a decrease in perceived stress and an improvement of multiple psychological factors associated with mindfulness abilities".
In China, Shi En and Luo Min are exploring the concept of scuba diving as a means of managing depression. The diving instructors and psychological consultants run a programme in Guangzhou called Deep Therapy, which offers diving training courses focused on healing the body and mind, and conduct experimental research into the potential psychological benefits of diving, such as alleviating stress and negative emotions.
"In our courses, all of the students and visitors are respected and understood," says Luo, a former journalist. "Scuba diving offers a change of scene. We take advantage of this and distract them from depression, guide them to focus on their breathing and the moment and then gradually help them move towards a brighter direction."
This emphasis on breathing technique is one of the reasons diving can be so relaxing.
"Breathing is hugely important in diving," says Dr Laura Walton, a British-based clinical psychologist and instructor development course staff instructor for the Professional Association of Diving Instructors (Padi), the world's largest recreational diver training organisation.
"If we're stressed and we consciously slow our breathing down, that physical change can affect our emotions, our mood and our stress levels. In diving that's something we explicitly learn " to breathe slowly and normally and deeply. It has a regulating effect; it calms us down."
Strapping on a metal tank and jumping into the sea might not be the most obvious way to achieve inner peace, but mindfulness, at its core, is about being present. Nowhere is this easier than underwater, where it is impossible to talk " let alone check emails or social media.
Chances are, you won't even notice the digital detox " the rest of the universe somehow simply pales into insignificance when you're watching a turtle eating its lunch.
"Underwater, it's kind of meditative," says Pauline Wong, an energy healing practitioner and diving instructor at Splash Hong Kong. "It's so different from your normal working life." Wong, a former interior designer, believes that diving and mindfulness can go hand in hand, and sometimes asks guests to slow down and visualise dives before jumping into the water.
There are many other reasons to take the plunge: diving means getting up close and personal with nature, and the sensory aspect of simply being in the water can often feel therapeutic. It's a social activity that relies on a "buddy system" of diving in pairs ("I've found, with the buddy system, that the non-verbal communication underwater means you tend to develop trust with people," says Wong) and it lends itself brilliantly to travel.
Not that you need to go far to feel the benefit of taking a dip if you are in Hong Kong " clown fish, scorpion fish, octopus and barracuda are just some of the species that can make an appearance during local dives.
"We do weekends away on the boat several times a year, and for me it's like leaving Hong Kong entirely," says Darren Gilkison, Padi course director at Splash. He is a former engineer who first took up the sport as an outlet to get away from what he calls "the day-to-day madness" of working.
"Even for me, working on the boat and running the boat, it's like a little bit of a holiday."
Diving is not without risks, which must be taken seriously, and it's important to progress at your own pace. Panic can set in rapidly when your mask fills up with water or you accidentally anger a trigger fish, but according to Walton, even these challenges can provide opportunities for self-growth and development.
"We need to fix problems under the water " we actually need to stay and fix them," she explains. "The best response is to just slow down, take a breath, think through the problem and then act upon it " and that's a basic life skill."
Swimming off into the Big Blue to chase hammerhead sharks isn't for everyone, but scuba diving's potential to make us all a little more mindful and provide unique moments of stillness may means it's worth a try.
After all, as Walton says: "You look at yourself in a whole different way once you start realising that you can breathe underwater."
When to go: For world-class diving and idyllic scenery, head to the Maldives, an island chain in the Indian Ocean where it's possible to see everything from reef sharks and manta rays to green turtles and barracuda. Diving conditions are generally good year-round, but January normally offers impressive visibility.
Where to stay: For non-stop diving, opt for one of the many live-aboards (boats that offer extended diving trips) operating in the Maldives. If you prefer to sleep with your feet on dry land, check out the luxurious Como Cocoa Island, which offers a range of Padi diving courses and excursions, as well as the chance to have a marine biologist accompany your group.
How to get there: the airport in Male, the capital of the Maldives, is served by direct flights from Hong Kong and 13 countries in East and South Asia, the Middle East, and Europe.
When to go: January marks the beginning of whale shark season in Thailand's Similan Islands, northwest of Phuket, which are usually only accessible from November to May. There are good chances of manta ray sightings too, and the dry season means warm water and great visibility.
Where to stay: Khaolak Merlin Resort is a deluxe, sustainable eco-resort that can help its guests organise diving trips or training courses with local dive operators.
How to get there: Phuket is served by direct flights from Hong Kong, other airports in Thailand, Australia, and 13 other countries in East and South Asia, the Middle East, and Europe. From there, it's a one-hour journey to Khao Lak, which is ideally situated for diving trips to the islands.
When to go: Raja Ampat, a group of islands on the western tip of Papua in Indonesia, is one of the crown jewels of Indonesia's impressive diving scene, offering year-round warm water temperatures and diverse marine life. The prime diving season runs from October to April, when the seas are at their calmest.
Where to stay: Misool Eco Resort is a private island resort and conservation centre with its own house reef and dive centre. There are 25 dive sites within a 15-minute radius of the property.
How to get there: Getting to Raja Ampat usually involves flying to Jakarta before transferring to Sorong, Papua.
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