When you pass through the waters, I will be with you; and through the rivers, they shall not overwhelm you; when you walk through fire you shall not be burned, and the flame shall not consume you. (Isaiah 43:2)
Imo, waters in this context – overwhelm being the keyword – represent the knowledge of sensory things that we have collected through our senses with rivers being the objects of sense perception. These have the potential to harm (overwhelm) us when not captivated in obedience to Christ (2 Corinthians 10:5). If you think about it, every temptation (fire) that the enemy ignites in us, is based on the misuse of some sensory object (ex. the temptations of Christ). If God is with us, as He was with Jacob, then neither the thoughts of the temptation as if fire will burn us (force us to consent to sin), nor the flame of desire will consume us (become a passion). A similar theme can also be seen in Psalm 124.
In contrast, the river of the water of life that flows from the throne of God, that is to say the knowledge of divine things and the gifts of grace that Christ bestows on us are pure and good for the cleansing of soul and body (Hebrews 10:22). This water nurtures the mustard seed of faith, it gives growth to the fig tree of righteousness and matures the grapes of the tree of holiness from which the intoxicating wine of theology is produced.