The given coordinates point to Suomenlinna main quay. You need to find the cannon I used to shoot the cache-box to mainland. Cannon is shown in picture and it’s somewhere in Suomenlinna.
When the cache-box crossed E25° it had been flying for 13,79 seconds, reached altitude of 2196,3 metres and was still in climb.
Initial velocity: 290 m/s
Gravity: 9,8 m/s²
Air resistance: None
Cache hit the ground 5 metres higher than firing altitude. The impact knocked over a big tree.
Cannonade from Suomenlinna #1
Cannonade from Suomenlinna #2