The northern part of the inlet, called Bøvling Fjord, is so shallow that it is sometimes completely drained by strong winds.
In the southwest part of Nissum Fjord, off of the peninsula Nørre Fjand, lies a small uninhabited island of 40 hectares called Fjandø.
The island's heath vegetation is kept in check by a flock of sheep during the summer, giving good conditions for bird life.
The project succeeded only at Felsted where a 13 km long dike was constructed and approximately 1400 ha.
But it was soon found that the soil was not suitable for agricultural usage, and the dike often breached under heavy storms; thus the project was abandoned in 1885.