Initially, there's the arrival post were people seem to be meeting up and arranging tenting groups of four.
Then we have three prefect run day-time activities: -The Obstacle Course in the Labyrinth Gardens -The Broom Relay Race on the Quidditch Pitch -The Potions Competition in the Cascade Hall
Then there's the Bonfire itself on the Quidditch Pitch, which takes place later that night. There's the fire, a band, fireworks, and socializing going on there.
Then there's the camping area which isn't really an activity so much as it is a place to post with your tentmates and possibly fall victim to a prank.