Let’s hope it was Fire Rescue training. A couple years ago a small CT pond that I was ice fishing had an open hole with caution tape all around it right in front of the launch. My thoughts were that some one had fallen thru. Turned out that it was rescue training with divers going in to practice.
Saw the Westwood Fire and Police rescue squad training at Buckmaster Pond some years ago.
Walked over to check out the practice and asked one of the shore bound officers "who drew the short straw to get dunked?"
He said that they all wanted to be the one, but the guy in the dry suit was the name picked out of a hat.
I will say it is impressive to see the operation in action.