This is the same angel first introduced to us in Revelation 21:9. On behalf of his heavenly sender (Hebrews 1:14), this angel functions as John’s tour guide as John must see several aspects of the holy city, the New Jerusalem. This is the third time the angel pointed something out to John (see also Revelation 21:9; Revelation 21:15); in Revelation 21:22 John himself observed the absence of a temple. That this angel drew the river to John’s attention implies that John (and hence we) must pay special attention to this river.
1 Then the angel showed me the river of the water of life, bright as crystal, flowing from the throne of God and of the Lamb