Jelaskan Finlandia dari BTR-60

Finland's Jäger battalions operated Soviet-built BTR-60R-145BM "Chaika" vehicles. These were upgraded to BTR-60PUM standard between 1996 and 1997. In 1991, seven conscripts of the Karelia Brigade drowned when their BTR-60 sank at Taipalsaari during an amphibious exercise because the vehicle was loaded incorrectly (top-heavy) and the roof hatches opened.

The usual nicknames for BTR-60 amongst the Finnish conscripts were Petteri (a male name), after the initials BTR, and Taipalsaaren sukellusvene (Taipalsaari Submarine) after the 1991 incident.