Rising below the col between Rocky Mountain and Balsam Cap, the Rondout Creek flows generally southerly down the slopes of Rocky Mountain into a narrow valley, receiving tributary Picket Brook on the left and three unnamed streams from the slopes of Peekamoose Mountain to the right. A mile or two from its source, it reaches some private lands and its first road, Peekamoose Road (Ulster County 42). It has dropped in its first two miles. It turns to the southwest to follow a wider valley, known informally as Peekamoose Gorge. Most of the land surrounding the creek is part of New York's Forest Preserve, "forever wild" and thus undeveloped. The rocky stream boasts several popular swimming holes, one of which is known as Blue Hole for the greenish tone of the deep water within. South of the small outlet stream from Peekamoose Lake, it is crossed and then followed by Peekamoose Road, which at first runs high above the creek but then close by it.