The calculated distance (air line) between Mer and Saint-Quentin-en-Yvelines is approximately 77 miles respectively 125 kilometers.
By car or train, the actual journey to Saint-Quentin-en-Yvelines is certainly longer, as only the direct route (as the crow flies) between Mer and Saint-Quentin-en-Yvelines has been calculated here.
Air line (approximately)
125 kilometers
67 nautical miles