This depth gauge is tough, flexible and lightweight with graduations printed on both sides.  Don't get tangled up with your old sounding line.

Determine how far down your sample is. Printed in meters, decimeters, and cm on both sides on a non-glare textured vinyl for maximum abrasion resistance. Withstands constant contact with mud or water. Includes attached snap ring. Can be used with our sounding weight without stretch. With a little adaptation, it has been used as a main line for water samplers... Tensile strength is 200 lbs.