Canada's Navy is marking what it calls a milestone for its controversy-plagued submarine program.

For the first time since Canada's four Victoria-class subs were purchased almost two decades ago, the navy says the fleet is now "operational", meaning three of the subs are able to conduct naval operations.

Two of the subs, HMCS Victoria and HMCS Chicoutimi will be in the water off Esquimalt, B.C. this week, while HMCS Windsor is currently operating out of Halifax.

A fourth vessel, HMCS Corner Brook is currently in dry dock in Esquimalt in what the navy calls a period of "deep maintenance".

Canada's submarines were bought second-hand from Britain for $896 million in 1998. Critics believe they've cost at least twice that much to fix, maintain and update to modern standards.

They've also suffered a series of troubling accidents over the past two decades, including a deadly fire on HMCS Chicoutimi in 2004, and a 2012 incident off Vancouver Island, where HMCS Corner Brook hit the ocean floor.

But navy officials are keen to put that all behind them and call the operational fleet a critical step forward. This week the navy invited a few members of the media to tour HMCS Victoria, considered Canada's lone "high-readiness" submarine.

The crew took our CBC cameras 60 metres below Juan De Fuca Strait to show off the sub.

Take a peek inside the HMCS Victoria with a 360º photo at bubb.li