Where “congregation” describes alligators gathering for a reason, “raft” describes how they look while doing it. Picture several alligators floating together at the surface of a still pond or backwater, barely moving, eyes and nostrils just above the waterline. From a distance, that low, flat silhouette really does resemble a raft drifting on the water.
This floating posture isn’t just for show. Alligators are ambush predators, and lying nearly motionless at the surface lets them conserve energy while staying alert to anything moving nearby, on the bank, in the water, or overhead. Floating in a group also has a practical side: shared vigilance. More eyes at the surface means a better chance someone notices approaching prey, or danger, first.
Rafting behavior tends to show up most in calm, warm water during the day, when alligators are thermoregulating and in no particular hurry to move.
Example: “A raft of alligators drifted near the reeds, barely a ripple giving them away.”
Related: Collective Nouns for Reptiles · What Is a Group of Alligators Called?