Far off the coast of Portugal, the Canadian special forces soldiers vaulted themselves out the back of a military Hercules transport plane with nothing but empty ocean below.

Well beyond swimming distance to the coast, it seemed like an act of dangerous derring-do, even for special forces soldiers.

But as the troops descended under their parachute canopies, a black mass broke the ocean surface — the Canadian submarine HMCS Windsor — for a carefully choreographed ocean rendezvous.

The soldiers clambered on board the sub, down the hatch and boat sank back below the waves.

“It takes a lot of courage to jump out the back of an airplane when all you see is water around you and just trust that something will pop up. It was pretty amazing,” Maj-Gen. Mike Rouleau, commander of Canadian Special Operations Forces Command said in interview.

“The submarine offers a really useful tool to be able to insert or extract from,” Rouleau said.

Indeed, with its new passengers on board, the submarine moved closer to the coastline, unseen below the waves. It surfaced again and the soldiers broke out their specialized gear — fast boats and outboard motors — that had been carried onboard the sub from Canada in a watertight compartment below its main deck.

“My job is to get them on target. They just drop into the big blue ocean and trust that we are nearby,” Rear-Adm. John Newton, commander of Maritime Forces Atlantic, told the Star.

This training happened last fall during an extended mission by HMCS Windsor in European waters, where the sub participated in a number of exercises with allied nations. While the military said publicly that those drills also involved working with the special forces soldiers, the exact details were never released.

Yet the daring parachute drop out of the Canadian C-130J Hercules highlights the growing relationship between the two shadowy elements of Canada’s military — special forces and the submarine fleet.

More and more, Canada’s four submarines are exercising with special forces soldiers — at least when the subs can be put to sea. Currently, only HMCS Windsor is available for operations and in recent days it has been sidelined in port with engine troubles.

“We’re operating a lot with the SOF (special operations forces). We really like working with them. It’s one of the coolest things we do ... That’s movie stuff,” said Lt.-Cmdr. Peter Chu, commander of HMCS Windsor.

Indeed, when French special forces found out about the exercise they too wanted to train with the sub though that didn’t happen because of scheduling challenges, Chu said.

Special forces soldiers are at the forefront of changing warfare, from large-scale confrontations to small teams training local militaries to conduct missions or carrying out those missions themselves.

Newton says there are natural synergies between sub crews and special forces troops — the stealthy aspect of their missions, working in the shadows.

“They are ... built for each other in how they think and act,” Newton told the Star.

Both Newton and Rouleau were on hand when trials were done earlier last year off the coast of Nova Scotia. Rough seas made getting onboard the submarine a challenge for the 10 soldiers who dropped into the water that time.

“Swimming onboard a submarine sounds fun. It’s anything but,” Newton said.

But they learned lessons from that experience — like flooding the sub more so the stern sat lower in the water, making it easier to get onboard.

Special forces soldiers have been working with the navy to hone their capabilities for maritime events such as ship hijackings, combating pirates, covert insert and extraction from coastal locations, intelligence and surveillance.

Canada’s special forces units have two dedicated depots — one on each coast — that store equipment and are equipped with briefing rooms and communications suites to serve as a hub in the event of a maritime emergency.

Loading... Loading... Loading... Loading... Loading... Loading...

In return, the navy has tapped the expertise of special forces troops, notably to help train new so-called “enhanced boarding parties.” These teams of sailors are specially trained to tackle situations with greater risk than might confront a conventional boarding party. The 10-person teams will be deployed on ships bound for risky areas.

Special ops soldiers also advised the navy in the purchase of new fast boats for those boarding teams.

Correction - June 13, 2016: The photo caption was updated from a previous version that mistakenly said the photo showed a chinook helicopter loaded with Special Forces for a training parachute jump into the ocean.