As a boy, Mark Warner was inspired to study the oceans after watching the adventures of Jacques Cousteau on TV. He would later discover, though, that unlike Cousteau, he was more interested in marine chemistry than in marine biology. Now, he studies how compounds produced by man – chlorofluorocarbons (CFCs) – enter the interior ocean to understand the ocean mixing and circulation pathways, a field called tracer oceanography. He has made measurements of these compounds throughout the world’s oceans, including collaborations with international colleagues in studies of the Seas of Okhotsk and Japan aboard a Russian research vessel, and of deepwater formation areas along the Adelie Coast of Antarctica aboard an Australian icebreaker. Mark has also been involved in studies of Puget Sound, including efforts to understand the low dissolved oxygen concentrations in Hood Canal.