The equipment that is sinking is a feller/buncher, that looks like this when it's on dry land:
The island has a harder crust on top of filling. It's a little like a piecrust, this land. If you break through the crust you fall into the filling -- and it's a long way to the bottom. When they drove the pilings for the local bridge they had to go 160 feet down to get to bedrock, so it's pretty safe to say that if it continues to sink, this equipment will be completely submerged.
They're OK until the water reaches the bottom of the turret. The electronics are usually in the bottom of the turret, and when they get submerged, you have 44,000lbs of dead weight to deal with. So what do you do in that case? You rent a pump and keep the water down, and you clench your teeth and order replacement electronics for around $5k. You keep the water down long enough to install the new stuff, and your hoe runs again -- and then you're just stuck. Instead of being stuck and immobile.
Bottom of Turret in water. Bad.
The last one of these that got seriously stuck required a 50 ton crane, 2 300 series excavators, a cat D7 and 10 truckloads of matting to get out. I'm curious what these guys will do.
I've offered them to use of my mats and timbers for free, provided they put them back when they're done with them.
If you're curious about the location, you'll find a link to google maps here. They're harvesting the poplar plantation that you see in the link.