An esplanade is an area that's meant to be walked on, especially beside the ocean or another body of water. An esplanade makes it possible to stroll beside the water without walking on the beach.
You can also call an esplanade a promenade. These flat, open areas are intended to be walked along, and they're sometimes also used for skating or biking. The original esplanades were similarly level, open stretches outside of fortresses that provided soldiers with wide visibility for shooting. In the US, another meaning of esplanade is a median strip beside or in the middle of a road. The word comes from the Spanish esplanada, "large, level area."