Hi Mike,
That's not such an easy question to answer - personal preferences and geography make this a bit of a poser.
For want of a better description, the country of Belgium looks like a narrow postbox - created in the 1800's as a buffer zone between the Netherlands and France. And the coastal area is only some 40 km long between De Panne and Knokke - and this includes the two ports of Oostende and Zeebrugge...
There are plenty of coastal camp-sites just north of the border with France - typically around the 10 km segment Koksijde - Nieuwpoort - Middelkerke - but they tend to be a bit cramped for space and only offer small pitches. But plenty of things to do for teenagers.
I really like Belgium,and always stay overnight in Damme (just north of Brugge) on my return commute from Rotterdam - but for our needs - only two adults - I couldn't recommend any of the coastal camp-sites.
But just 10 km inland and close-ish to Brugge, somewhere like "Camping Klein Strand" with it's own water park and inland beach - has a good reputation - 100 m2 pitches - and loads to do.
Otherwise, "Camping Blaarmeersen" in Gent (located in the City Recreation Park - loads to do) is rated as the best camp site in Belgium
Take a look through the ACSI on-line review site:
http://www.eurocampings.co.uk/en/europe/belgium/west-flanders/
for the coastal region inland to Brugge, and if you want to find a review on Camping Blaarmeersen - you just need to navigate to the Gent page
As I said, I really like Belgium - eating out is the equal of France, the beer is seriously good, the cities of Brugge and Gent are absolute gems, and the region you plan to visit is the Dutch speaking area (so you can forget any French you might know) and English is widely understood.
Robert
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