There are three beaches at Crystal Crescent; two are textile while the third one is clothing optional by tradition. The two textile ones are close together, and near the parking areas. The clothing optional one is a 1km+ hike along a well-maintained trail. People seemed to keep their clothes on along the trail, so I would not advise stripping down until you reach the beach, even though it would be really nice to hike nude to the beach.
If you get to a sign that says "End of Trail Maintenance: Proceed at own risk", you've just gone past the clothing optional beach, although I highly recommend proceeding at your own risk because there are some nice rocks to see.
Back to the clothing optional beach... There is no signage indicating that it is clothing optional. I don't think it is a legally-sanctioned c/o beach, but it seems to be accepted as such. On a hot summer afternoon, there were perhaps a dozen people on the beach, all male, and most nude. I'd say the age range was 30-70, or maybe 40-70. Most were lying down. A few were standing up, which I find a bit weird, but I guess they're allowed to.
The beach is sand, with some annoying prickly vegetation embedded in it here and there. Once you get into the water, the surface is round rocks about 20cm in diameter. They are not much fun to walk on. I should have brought my water shoes.
The water was very cold, but not icy-cold as at the nearby textile beaches. This is the North Atlantic, but the water is shallow near the clothing optional beach, so it warms up slightly. I am told the Gulf Stream sometimes brings warm water to these beaches, but that was not the case on the day I was there!
The drive from downtown Halifax was about 40 minutes. The upper parking lot is slightly closer to the clothing optional beach, but it doesn't really matter. There is a Halifax Regional Municipality bus that might get you within a couple of km of the park. Crystal Crescent is a provincial park. Alcohol is not permitted, which I think is a good rule. Facilities consist of outhouses. There is no running water, so bring your own drinking water. Parking and admission are free, so I'm not complaining about the lack of showers or other luxuries.
The beach was free of litter. People seem to take very good care of it. There were no smelly barbecues. There was no loud music. There were no annoying motor boats, no helicopters, just waves. Except for the chilly water, it was just about perfect.