1of5 In an undated photo, young women enjoy a common way to beat the summer heat in pre-air-conditioned San Antonio, by going to swimming holes along the area’s many streams and rivers.File photoShow MoreShow Less 2of5The Blue Hole in Wimberley is known as one of the best swimming holes in Texas, seen here in April 2015.Jennifer Hiller /San Antonio Express-NewsShow MoreShow Less 3of5 4of5 The beautiful Frio River, with Old Baldy in the distance, just outside Garner State Park, near Concan.Courtesy Dale BlasingameShow MoreShow Less 5of5 My dreams of going to the dashingly dangerous yet beautiful Jacob's Well in Wimberley were dashed this week after I perused their reservation website and learned reservations were almost completely booked.