Welcome to my science fair project. The purpose of my experiment, How does saltwater mix in an estuary?, shows how dense the saltwater mix from five different locations along an estuary. An estuary is a bay or sound where fresh water from streams and rivers empties into and mixes with salt water from the ocean. I am trying to prove that the water closest to the ocean is more dense than the water farther away. The five samples that I took will help me prove my hypothesis.