Looking at the severed parts, it doesn't seem like they'll live long. I wonder how long they'd survive after something like that.
It looks like something out of CockroachPunk 2077
I am unsure they really care how long it lasts especially when you create something like this.
As long it carries out it mission for a minute of two. Send it to some underwater fibre optic cable and use it as a depth charge to blow it up.
No more requirements for anchors.
The title says "hours-long diving" so at least a few hours i guess...