”M/S Merkurius” is a car and passenger ferry built in 1999 by “Trondheim Verft AS”, Norway and equipped by Tenö shipyard, Sweden. It was delivered on 6th December 1999 to “Vägverket Färjerederiet” under the name “Vaxholmen” with an inventory number 335. Initially, it was assigned the route “Vaxholm–Rindö Västra”.In 2010 there was a modernisation in the road administration system and a new entity of “Trafikverket” was created. From 2010 “Trafikverket Färjerederiet” manages and runs the ferry. In 2011 new engines of a type Scania DI16, 2,000 hp (1,470 kW) were installed. In 2012 it was transferred to the line Slagsta–Jungfrusund. On 21st of October 2014 it was renamed to “Merkurius” and about a month latter, on 29th of November 2014, it was assigned the line Öregrund–Gräsö.