I was always risk-averse until I found myself 2m underwater staring at a flash mob of fish

Old dogs, or in this case, old-ish ladies, can learn new tricks while they travel. Or can they? HELEN HAYES combines a tropical escape with a personal challenge.

I cannot believe my eyes. I can see hundreds, possibly thousands of fish. They are all shapes and sizes and a kaleidoscope of colours. It makes me forget that I am two metres deep and relying on a breathing apparatus that makes me sound like Darth Vader. This is the reward for going way, way out of my comfort zone, experiencing my first - ever - scuba dive.

After playing it boringly safe and being completely risk-averse for more decades than I care to remember, the idea of combining two of my favourite travel experiences, with a twist, took hold of me. I love travelling by train, and I adore being in the water, especially in the tropics where said water is that beautiful turquoise blue. So a reef by rail adventure came to fruition.

I have an appetiser to the aquatic degustation ahead on a day trip from Bundaberg to Lady Elliot Island. A scenic flight to the island and back delivers humpback and manta ray spotting from the plane windows. Once on this small but mighty coral cay, I have my first foray into the blue on a snorkelling tour, seeing black-tip reef sharks and coming face-to-flipper with three turtles.

Back in Bundaberg, I catch the Spirit of Queensland train to Townsville, an overnight journey spent cocooned in a RailBed. From the station in Townsville, it's a short taxi ride to the Breakwater Ferry Terminal and a 20-minute transfer with SeaLink to Magnetic Island, and it's on "Maggie" where my adventure really begins.

Magnetic Island is the only fully self-contained island in the Great Barrier Reef Marine Park, or as one of the locals tells me, "the only island in the reef with its own postcode". It has 23 beaches, forest hikes where you can spot koalas, and many activities on and under the water, from sailing and SUPing to snorkelling and ... scuba diving.

My first challenge is a three-hour introductory dive with Pleasure Divers, instructor Chad talking me through the process. I had already completed a medical report before I left home and had the all-clear. Chad goes over the basics on what happens to your body when you go under water, and shows me the equipment and how it works.

After passing a quiz it is on to the next phase - getting the gear on and going into the pool. The oxygen tanks are far heavier than expected, but thankfully Chad does all the work getting me ready. Once in the pool I have to achieve three things - clear water out of my mask underwater; take the regulator out of my mouth, blow bubbles and put it back in; and swim around the pool breathing smoothly. It takes a while to do the mask clearing properly - mostly because my heart is racing and I am not thinking straight. But Chad is patient, and I get it eventually.

From here, we go to nearby Alma Beach, put the gear back on and waddle into the water. Before we submerse, Chad goes over the signals for "OK", "up", "down" and "are ears OK" - and once again I practise clearing the mask and taking the respirator out. Before I have time to stress, we are beneath the surface and I am instantly entranced by the water, the coral and the sea life. Chad gives me the slow-down signal because I am off like Mollie O'Callaghan.

The beauty about diving, Chad had espoused earlier, is that it is meditative, and you really are in the moment. We see stingrays, parrotfish, a cowtail stingray, batfish and a whole lot more. Before I know it, we are in shallow water and standing up near the beach. The feeling is one of elation and I cannot get the smile off my face.

Introductory dive No. 2 is a different kettle of fish. The Adrenalin Dive boat bumps its way out on a 2.5-hour trip to John Brewer Reef. On the way, we fill out forms, and I do the educational session again before peeling into a wetsuit for the two sessions at this remarkable location - right on top of the Museum of Underwater Art (MOUA). My scuba dive is on in the second session - I snorkel for the first one - and before I have time to worry about jumping into the ocean in the middle of nowhere, I'm in and descending to two metres, where guide Brendan makes me and another woman do the two tests - the mask clearing and taking the respirator out.

After catching the Spirit of Queensland train from Townsville to Cairns, my third and final introductory dive is with Dreamtime Dive and Snorkel. I am on a five-hour tour that includes visits to two reefs - Flynn and Milln. I drop down with guide Ethan who has me on one side and a young man on the other. It is a short dive but the bommies are awash with soft corals and fish. On the way back to Cairns, we hear the Dreamtime stories about the reef, and enjoy live demonstrations of traditional dances and the didgeridoo. It adds another element to what is already a dream day out.

After taking off from Cairns I marvel at the coral reef patchwork down below, and my mind goes straight to the magnificent world that lies beneath. A world I just might visit again - age be damned.

The writer travelled courtesy of Tourism and Events Queensland and Queensland Rail