Sinkhole in Tuhala karst area. The geologist standing at the bottom of the hole for size comparison is 195 cm tall.
<a href="//commons.wikimedia.org/wiki/User:CarlJohanSveningsson" title="User:CarlJohanSveningsson">CarlJohanSveningsson</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>