One of the largest vessels in the BC Ferries fleet returns to service today on the Tsawwassen to Swartz Bay route after undergoing months of upgrades.

The Spirit of British Columbia, one of only two Spirit-class ships in the ferry fleet, has been undergoing its mid-life upgrade since last fall and has also been converted to run on natural gas.

The ferry corporation says the switch from marine diesel makes the big ship much cleaner for the environment and amounts to taking the equivalent of approximately 2,500 vehicles off the road every year.

The Spirit of BC's sister ship, the Spirit of Vancouver Island, undergoes the same refit starting this fall.