Not many people visit, but if you are going to Belgium this summer be sure you go to the Belgian coast to visit the beach town of Knokke, which locals call it the "St Tropez of Belgium". It is definitely as pretentious and fashionable as St Tropez. Oh yes, while you there do pass by the Westhoek nature reserve. It's a nice place to relax and see wildlife.
The Belgian Coast is very crowded in the summer and you will feel very claustrophobic. That being said, it is nice there, especially in Ostend and De Haan, which hasn't been ruined by 1960's concrete architecture, unlike most of the Belgian Coast.
The best-known resorts are Blankenberge (boasts a classic pier built in 1933), De Haan (surrounded by forests and dunes), De Panne (home to the Plopsaland theme park), Knokke (home of the rich), Oostende (great connection by ferry to England), and Zeebrugge (located nearby Bruges).