The Arizona Hot Springs, when accessed from the river, make for an exceptional and very easy side-adventure. To access the springs, hike away from the river, and turn into the left canyon as the trail forks. From the turn, follow the creek for around 1000ft through a slot canyon. You will arrive at the base of a 20ft ladder. It is necessary to climb the ladder to reach the springs themselves. Once you climb, you will reach the first of a series of hot springs separated by sandbags. The temperature of the springs gets hotter as you ascend through the slot canyon, reaching around 110 degrees Fahrenheit at the upper pool. Make sure not to submerge your head, as these springs could possibly contain the deadly amoeba Naegleria Fowleri. You can read more about the amoeba, here.
NPS hiking instructions to the hot springs can be found, here.