To find out about the microscopic life in the valuable estuary environment, it is usually necessary to be near the water. This dry lab offers an alternative, using authentic data and a simulation of plankton sampling. From the types of organisms found in the sample, middle school students can infer relationships in the biological and physical environment of an estuary. A "Science Activities" classic, the activity was originally published as "The Estuary" in the February/March 1983 issue. (Contains 6 figures, 4 notes and 3 resources.)