The Hudson River's depth fluctuates wildly as one sails up its length. In many places, most notably just off West Point, the water is so deep that its ambient temperature often varies considerably between the bottom and the surface.
Although water temperature has relatively little effect on the Half Moon or its crew (with the exception of extreme temperatures, as Captain Hudson understood while battling the polar ice during his arctic expeditions), it can have obvious effects on the local ecology.
On the Half Moon, our students take temperature readings both from samples drawn from the surface (usually as part of comparative temperature studies), and from the water column, which means water collected from different depths at a single location.
