Take route 41 from the number 4 highway, following signs for the national park. Keep following, and turn left just before the naval base. The road passes some kind of refinery, then turns sharp right. In the dry season you shouldn't have any issue with a campervan. I was on a motorbike and the terrain was no problem. You'll arrive at an amazing little beach which you'll quite likely have all to yourself. Park up your van, pitch a tent or just crash out under the stars on the beach.

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