The Better to See With

WHOI technician Jefferson Grau inspects a new Alvin viewport (window) to make sure it doesn’t contain bubbles or inclusions such as bits of dirt, which could cause the viewport to crack under the extreme pressure of the deep sea. The viewport is made of a kind of plastic that is firm but not brittle—under pressure it will actually change shape. As part of a major upgrade, the research submersible is being outfitted with more and bigger windows than it had previously, to give the pilots, researchers, and observers inside a better look at the watery world they will visit.(Photo by Matthew Barton, Woods Hole Oceanographic Institution)