Isles of Scilly Police are appealing for witnesses after a memorial bench was damaged on St Mary's last week.
The three-seater bench, in the Longstone area, was damaged between Monday September 18th and Friday 22nd.
It was purpose built from composite materials to prevent rot and has a commemorative plaque.
The owners of the bench reported the damage, which they believe was done on purpose.
PC Richard Wiltshire said: "One of the seating slats was broken off and the support beams underneath are split, which would suggest that someone jumped up and down on it, although we don't know exactly what happened."
Islanders or visitors who have witnessed someone jumping on the bench are asked to contact the police station on 01720 422444 or 101.