Middelharnis has a shopping area called D'n Diek. This shopping center settled itself on a dike which used to be the last barrier for the town from the Haringvliet. The town hosts two public and one Christian high school. Middelharnis has an inland harbor with connection to the Haringvliet. There is also a small beach which can get very crowded in the summertime. In Middelharnis the old main street has the old municipality building.
Het Laantje van Middelharnis (Avenue of Middelharnis) by Meindert Hobbema (1689).