In order to assist the rescue aircraft in locating their spacecraft at sea, Apollo crew members would use sea dye marker kits similar to this training version to make their location more apparent to searching aircraft. To use, the astronauts would pull a tab on the package to expose the dye chemical and then put it in the salt water. The chemicals create a large brightly colored cloud in the water. The kit was part of a standard survival pack called rucksack #1, which also included a three-person life raft, CO2 cylinders, three sunbonnets, a sea anchor, and lanyards. These objects were to assist the astronauts survive the rigors of the sea prior to rescue and last them up to 48 hours.
This non-flight sea dye marker kit was transferred from NASA to the Smithsonian Institution in 1979.