Significados de fierce undertow en inglés

Listening now to his son's chatter, the boy talking to himself, Simon felt the fierce undertow of parental love: the painful protectiveness.

In its place, dark water rolled over the horizon, poured into my lungs, black and brackish, pulling me down in a fierce undertow.

Although it is only one and a quarter miles from the shore, the water is freezing and the fierce undertow of its currents deadly.