RedactedNarrative: On May 2, 2021 at approximately 1138 hours Deputy and myself were conducting boat patrol on Canyon Lake in unit LP40 near the camping and dock area known as Beer Can.  We were traveling at a moderate pace when we observed a red boat being towed by another watercraft traveling away from the docks.  
  
  We both recognized the red boat as a watercraft we had towed to the Beer Can area approximately 5 minutes earlier when the boat had been unable to start its engine.   During the previous call for service we had towed the boat approximately a mile from its initial location to the Beer Can docks.  We had safely disconnected the boat from our tow line and pulled away from the dock without issue.  The driver of the disabled boat was speaking to another boater at the dock and asking for a tow back to the main docks as we pulled away.  I did not observe any damage or issue with the red boat we had towed back and it appeared to be riding correctly on top of the water.  
  
  We were approximately 1/4 mile away from the two craft when I observed the back of the red boat become swamped by a wave of water.  I noted the back end of the boat immediately began to sink and started to inform MCSO Dispatch we had a boat which appeared to be sinking.  
  
  As we neared the location I could see the boat rear end was fully submerged and the four passengers were in the water and scrambling for life preservers. We updated MCSO Dispatch, telling them the boat had sunk and pulled towards the area to assist with extracting the passengers from the water.  
  
  
  The passengers all swam to the nearby boat, which had been towing them, and climbed aboard.  
  
  Deputy brought us alongside the partially submerged boat, which still had approximately three feet of its bow sticking out of the water, so we could attempt to attach a tow line to it and pull it to shallower water.  I leaned over the water to attach the rope to the boat and saw it quickly sliding deeper under the surface until it was fully submerged.  I was unable to attach the rope before the boat sank beneath the surface.  I informed MCSO Dispatch the boat had fully sunk and all passengers were out of the water and safe.  Deputy provided MCSO Dispatch with the GPS Coordinates.  The approximate depth of the channel at this location was 96 feet deep.  
  
  We made contact with the boat which had been towing the red boat.  It was now occupied by the four passengers from the red boat as well as the original four boaters who had been inside the tow vessel.  
  
  We instructed the driver of the boat to follow us back to the main docks so we could further conduct an investigation.  
  
  Upon arrival at the main docks at the MCSO Aid Station I separated the driver of the tow boat from the group and interviewed him.  He was identified.
  
  After we had assisted the red boat to the dock and left the area, Operator 2 had agreed to tow the red boat and its passengers back to the main docks.  Operator 2 told me he had used his ski rope to pull the other boat and had just started out from Beer Can.  He estimated he was traveling at 10 MPH, just a little bit above idle.  Operator 2 said suddenly the nose of the red boat seemed to come up and approximately 20-30 seconds later the boat sank.  He said he immediately disconnected the rope and pulled his boat away and then brought it back around to assist the passengers.  When I asked him if he had observed any other boats in the area which had come close to him while towing the boat He said he did not believe so.  This concluded my interview with him.  
  
  I then spoke to witness who was an original passenger in the boat doing the towing.  Witness told me they had been towing the red boat back to the main bay.  Witness said she looked away for a moment and suddenly hear yelling.  