This image is a close up picture of two young Steller sea lions swimming in the waters of Resurrection Bay, near Seward, Alaska. Only part of their bodies can be seen. Both animals are swimming away from the photographer, and are swimming quite rapidly, creating a wake to the side of their head and body. The left animal is closer, but only it's head can be seen above the water. The right animal is a little ahead of the left animal, but is closer to the surface so that the back of the animal is visible. On it's back the animal is carrying an instrument. This instrument measures about 3 by 3 by 5 centimeters, and has a 20 centimeter long straight wire antenna stickking out of the back of the instrument. The instrument is glued to the fur of the animal's back via a slightly larger patch of about 10 by 20 centimeters. We use a thin layer of quick setting epoxy to glue this patch to the surface of the fur, so that the fur does not get damaged. These transmitters are used for tracking the location and behavior of the animals after their release, for periods of 1 to 4 months, depending on how long the transmitters stay on teh animal before they fall off. The transmitters uplink to orbiting satellites when at the water surface, or when the animal is hauled out. This allows us to determine the location of the animals, and gives us information about their diving and feeding behavior.