Scuba diving at 90 feet in Maine: why do things look so colorless down there?

Yesterday, I went for a dive at the Rachel Carson Salt pond up in New Harbor, Maine. Down around 90 feet, much of the light in the visible spectrum (~400-700nm) has been attenuated. Basically, this means that the light is absorbed as it passes through water. Think about sitting under a tree on a sunny day with the sun directly overhead: the bigger the tree, and the more leaves between you and the sun, the more stuff the sunlight needs to pass through to reach you, which means less direct light reaches you under the tree. But were you sitting under a short tree with fewer leaves, more light reaches you directly, since there's less stuff in the way. The leaves on the tree are like particles in the water and the deeper you swim, the more particles there are between you and the sun (i.e. there's more stuff in the way).
  What makes this phenomenon neat, is that different colors of light are absorbed and scattered by the particles in the water at different rates, so, for example, at 90 feet, things all look pretty blue/green since the red light is absorbed/scattered faster than the blue/green light. To illustrate this, I took 2 pictures of a northern red anemone (Urticina felina) at 90 feet (or ~27m): one with natural light and one with a flash. The flash is akin to letting the sun shine directly on the anemone in the photograph, that is the red light hasn't been absorbed yet, since the light source is less than 1 ft (~.3m) from the subject.