Are the devices suitable for the marine environment?
Suitability depends on the proposed research. We have successfully deployed the devices on a number of seabird species, tracking them for short-term trips recording very-high resolution positional information. In these cases, we package up the devices in heat-shrink tubing (waterproof and bird-proof) and attach the devices using Tesa tape.
The devices record GPS locations and transmit data via radio signals. Both of these features do not work underwater (as radio signals don’t really penetrate water). As such, the devices cannot track GPS locations or transmit data underwater. However, given sufficient time they can record fixes and relay data to other devices when animals are on the surface (or out of the water).