9 Refreshing Swimming Holes Worth Exploring Near Philadelphia Escape the humidity in these natural swimming spots not too far from the city. Tap into your adventurous side and cool off in these natural swimming spots within a three-hour drive of the city. / Photograph of Beltzville State Park courtesy of the PA DCNR. When temps soar, it’s so satisfying — and much-needed — to take a dip in refreshingly cool water.