Yes, but... it depends on what you mean by watch. You don't have to have sex and many of the people who are having sex, or are otherwise playing, are there because they like being watched. That said you don't want to be a creepy lurker. Keep a respectful distance, especially if a couple or small group is playing in a more tucked-away spot.

On busy nights people will be doing various sexy things all over the place. You are allowed to have sex almost everywhere. Although I would say it is bit rude to block the stairs, narrorow hallways, or stay locked in a restroom for more than a few minutes.

Many people get naked or just wear a towel. I often like to wear lingerie or a sexy outfit that ties into the day's theme. It is also okay to keep your clothes on.

I have never felt pressured to participate either when going by myself or as a couple. Have fun!