Based on the popular BBC Radio 4 dramas "Annika Stranded" (her surname is in program notes as "Strandhed") which also starred Nicola Walker, but is set in Norway. The radio series ran 2013-2020 and the episodes are 15 minute monologues. These have sound effects but only Annika speaks, either addressing other characters or confiding to the listener. Similarly, in the TV series Annika talks to the viewers through the 'fourth wall'. Writer Nick Walker reuses/modifies some of the plots. In the radio series Annika has a son Tor whose father is an officer in 'the Reindeer Police'.
On Monday, 8th August 2022, UKTV announced that they had co-commissioned Black Camel Pictures to produce a 6-episode second series of the crime drama with Masterpiece and All3Media International. Series two would be broadcast on UKTV's crime drama channel Alibi in 2023.
Annika's police jacket has the logo HH for Helly Hansen, the Norwegian clothing brand.
In three of the episodes Paul McGann appears. He worked with Nicola Walker on the Big Finish audio dramas including Dark Eyes based on his role as The Doctor.
Technically "marine" means 'pertaining to the sea or ocean'. The MHU also deals with freshwater fatalities.