OVERVIEW: The PM04 (Sea Mine 2000) is a Finnish air- or ship-deployed bottom mine designed to detect and destroy surface vessels and submarines in littoral and coastal environments. It uses combined magnetic, acoustic, and pressure sensing for selective target engagement.

DETAILS: Developed by Patria starting in 1997, manufacturing began in 2004 under a Finnish Navy order; deliveries continued through 2008. The mine is fitted with magnetic total-field magnetometers, passive narrow-band acoustic sensors, pressure fuzes, arming delay counters, and target discrimination logic. Designed for stealthy seabed emplacement, it features low-visibility coatings and programmable deployment profiles via aircraft or minelayers. Its influence sensor suite enables engagement only when ship or submarine signatures meet predefined criteria, reducing unintended detonation and civilian risk.

FUNCTION: Once deployed, the PM04 rests on the seabed and activates after a timed arming delay. It continuously monitors baseline magnetic, acoustic, and pressure signatures, triggering detonation only when larger vessels and submarines matching the programmed target profile pass overhead.

NOTE:
IOC: 2004
Operators: Finnish Navy
Platforms: Pansio-class minelayer, Pohjanmaa-class minelayer, aircraft (HEA-1970 helicopter not confirmed)
Conflict used in: No combat use; employed in Finnish coastal defense and training exercises

SOURCE: cmano‑db.com PM04 profile: https://cmano-db.com/weapon/3859/ ; Defence‑Aerospace article on Finnish Navy order: https://www.defence-aerospace.com/patria-wins-finnish-navy-sea-mine-order-dec-10/ ; DBpedia Sea Mine 2000 record: https://dbpedia.org/page/Sea_Mine_2000