Henry Steinberg, Julia Clarke and Laura Verhegge do their first tether dive with Chris off the shores of Race Rocks in Race Passage. The apparatus for the dive was constructed by Henry Steinberg, a Pearson College diver, as part of a project in his PADI Divemasters course. This type of diving is useful for research purposes when one wants to sample jellyfish, salps or other macro-planktonic life forms which may otherwise be damaged if collected in a towed plankton net. It is also necessary as a safety measure for drift diving when the bottom is beyond safety limits, and there are currents involved such as here in the Strait of Juan de Fuca.