Way back in the late 1800's and early 1900's, before logging trucks and good roads were around, when a log would be cut, the sawmill guys would float it and many others down the river.
Some of the logs would sink to the bottom of the river, leaving them there for close to a century, only to be sonar-located and dredged up.
You can't grow that! We only have access to about 300 more board feet of it, and you'll be hard-pressed to find it somewhere else, so don't wait
Janka Rating 510 lbf