The forest is lush and moist since it is the flood plain of the river. The trees are black walnut, red maple, tupelo, white and black oak. Spicebush is abundant in the moist earth too. This path will bring you to the all-important river. Fresh water seeps and springs arise from its banks. The clean shallow river flows south all the way to Great South Bay, and it arises from freshwater pools near Middle Country Road. This is the longest river on Long Island at 10 miles long. Eight miles are fresh water, and 2 mix with salt.