Captain Margrith Ettlin, Viking’s first female captain and in charge of the new expedition ship Viking Polaris was blunt when passengers met her for a sailaway party in Ushuaia, capital of Tierra del Fuego.  “This is not a vacation – it’s an expedition!”

How right she was.  Safety was drilled into us and there were plenty of lessons available that underscored that this was no simple pleasure cruise.

Our trip to Antarctica was a privilege.  Thousands have taken this journey to the ends of the earth to learn about our planet and the need to preserve.

But the tragic end of the Titan submarine search, with its five passengers lost after a massive implosion, may well pose questions over the growing business of taking travel to greater extremes: not just the depths of the ocean, but into space.

Extreme adventures that plan to send guests into space and the most inaccessible depths of the ocean at more than $125,000 a trip is a booming business.

Richard Branson’s Virgin Galactic is due to blast off shortly with fee paying passengers on board, and Titan journeys cost an eye-watering US$250,000.

Such voyages have become more accessible as technology has improved and the world has become more connected, luxury travel advisers told The Wall Street Journal.

I paid no such sum for my 20-minute journey into the depths on board Ringo, a US$5 million submarine with seats for six and a fully-trained pilot when we visited Antarctica aboard the Viking Polaris last year.

But reassuringly, safety and the fact that this was no ordinary excursion was a constant as we travelled to our sub and conducted inside the chamber.

At the start of our Antarctica journey, safety was to the fore. We were all taught how to get in and out of the ship’s fleet of sturdy Zodiacs that would speed us to the ice.  And because I had signed up to experience one of the ship’s two mini submarines, I was given special treatment.

First, I was asked to do some push ups to test my ability to bend my knees (the subs are small and require an extra level of dexterity to get in and out.

Then, there followed a 20-minute lecture on how a mini-sub works and what its safety features are – particularly in the unlikely event of things going wrong 100 metres beneath the icy Antarctic ocean.

And when we finally boarded Ringo – no prizes for guessing why the ship’s two gayly painted submersibles are called after members of the pop group The Beatles – we were treated to another safety lecture on what to do in the unlikely event of anything going wrong.

You can witness the lecture and our decent on our video here.

So what’s it like to dive under the freezing waves of Antarctica – and how much skill and training is involved in piloting them?

Safety was front and centre at all times.

Before we were taken to the sub in a Zodiac, we donned booties and lifejackets. And before we submerged, our pilot, 2nd officer (submersible) Daniel Petersson, went through an aircraft-like safety briefing and finally asked if anyone had changed their minds.

No-one had.

A special motor launch is on standby for rescue throughout the dive and Daniel relayed every move he made by radio to the surface vessel.

Before the dive, we were weighed to make sure the three passengers on either side of the sub’s thick acrylic viewing bubble were balanced. We attended a safety lecture at the start of the cruise with the warning:  if you don’t attend, you don’t go down.

The briefing included what to do if the pilot become unconscious and how the sub could be made to automatically float for the surface – a fail safe mechanism that means if the pilot is inactive for a certain time, the vessel jettisons its ballast so it can float to the surface.

Once ready, Daniel filled tanks that sent us an amazing 100 metres to the sea bed, where guests could witness fish, plankton, and plant life. Some were able to see penguins swimming by.

As we returned to the surface we again got a briefing on how to leave the submersible.

Our Zodiac crew were waiting to assist us out of the sub and back to the ship.

Perhaps the best part was sitting in Expedition Centre with Dr Daniel Moore, the Polaris chief scientist, who identified everything we had seen from our pictures.

Ringo and brother George are proving very popular, and while George did need some maintenance during the cruise – passengers had their dive cut short – we were extremely impressed with the safety.

Ringo the yellow submarine

Daniel told us he had trained for 25 days and had a further five days of rescue training to qualify for the position, and he was already a ships officer.

The submarines have six-centimetre thick acrylic viewing domes, weigh in at 11 tons and can support life for 96 hours. There is even a worldwide rescue guarantee by the company that builds them to order, Uboat Workx in Holland.

Viking is not alone in offering journeys beneath the waves. Scenic’s discovery yachts, Eclipse I and II, both have subs.  As do Seabourn’s Venture and Pursuit.

I found the experience a great addition to a cruise that was centred on the science and sustainability of this amazing part of the planet, and I had total confidence in the crew that were overseeing the operation.

Whether or not the experience of Titan deters this type of true adventure remains to be seen.

The Wall Street Journal quoted Mike Reiss, the 63-year-old writer for “The Simpsons” who went down last July.

He says he doesn’t like traveling, but his wife loves it, which is why he accompanies her. He says the risk warnings on the Titan were very clear to him and he took the trip knowing death was a possible outcome.

Despite this risk, he says travellers who have taken a voyage in the Titan, himself included, aren’t thrill seekers.

“They’re not hang-gliders or skydivers. They’re explorers and they’re travellers who just want to see things, and that goes for me,” he says. “I’m not going to jump out of an airplane but I will go to Iran to see what that’s like or Iraq or The Titanic.”