If you fancy a quiet afternoon then this is a nice spot worth a visit. You will probably need a car though as the crater is off the main road and public transport frequency would probably require this to be a whole day visit.........and other than the crater, there's not too much to occupy you for a whole day. The crater is signposted from the main road.
The crater itself is more of a curiosity rather than a major site but it is very accessible. Apparently the crater was created 2700 years ago and is in fact a cluster of several small craters scattered over the Estonian countryside. The largest crater is about 100m in diameter and is filled with water.
Scandinavian legend has it that this is the sun's grave and because the sun chose to be buried here, it blessed the Estonian people.
Don't expect to be stunned, but it is an attractive spot, very accessible, and in the Northern Hemisphere, relatively unique.