Adam Clarke on John 3:23

In Aenon - This place was eight miles southward from Scythopolis, between Salim and Jordan.

There was much water - And this was equally necessary, where such multitudes were baptized, whether the ceremony were performed either by dipping or sprinkling. But as the Jewish custom required the persons to stand in the water, and, having been instructed, and entered into a covenant to renounce all idolatry, and take the God of Israel for their God, then plunge themselves under the water, it is probable that the rite was thus performed at Aenon. The consideration that they dipped themselves, tends to remove the difficulty expressed in the note on Mat 3:6. See the observations at the end of Mark.