"Crossing the River" is a classic problem-solving puzzle that involves transporting items across a river using a boat. The challenge typically includes a limited number of trips and specific rules about what can be left together on either side of the river. Common elements include a farmer, a wolf, a goat, and a cabbage, each with unique constraints. The objective is to successfully get all items across the river without violating the rules, such as leaving the wolf alone with the goat or the goat alone with the cabbage. This puzzle encourages logical thinking and strategic planning.