There are few general analyses of the interest of onshore wave energy converters (onshore WEC) in terms of resources, efficiency and cost. The case of The Channel on the Atlantic coast of France is chosen here to illustrate the issues related to onshore WEC development. The paper presents a list of potential sites with their characteristics and a more in-depth analysis of a few sites. For four onshore WEC families, the production is given with a method of calculating the efficiency and economic analysis is carried out to estimate the energy cost at two selected sites. Annual wave power levels are maximum in Bayonne with 24 kW/m, and the lengths of useful dikes vary from 60 m in Molène up to 4000 m in Cherbourg. Wave reflection on the dike is an advantage in terms of energy production. The oscillating flaps constitute the systems with the highest efficiency, and the float systems have the lowest levelized cost of energy (LCoE), followed closely by the oscillating flaps. Oscillating water columns and overtopping systems have nearly five times these LCoEs. With mass production, costs of oscillating floats and flaps will approach those of other renewable energies such as solar and wind power.