The MAKO Spearguns Marker Float is a great way to mark your dive spot while diving.  Use multiple floats to mark the perimeter of your favorite wreck, reef or debris field. 

Recommended accessories are the MAKO utility diving reel for rapid deployment and accurate line management, and the MAKO folding anchor.

When your sonar is marking your spot, with line running through the buoy, drop the anchor and buoy, press the release button on the reel and let the line pay out.  Once it stops, drop the reel in the water and you have marked your spot.

I like to drop 4 of them (N, S, E and W) to keep me within the grid so I am not wasting drops by diving off the structure.

Measures: 11 inches long x 5 inches diameter