"Three Missionaries and Three Cannibals" is a classic river crossing puzzle. The goal is to transport all six individuals across a river using a boat that can carry only two at a time. The challenge arises because the cannibals cannot outnumber the missionaries on either side of the river at any time, or the missionaries will be in danger. To solve the puzzle, players must strategize the movements of the missionaries and cannibals to ensure safe passage. The puzzle requires careful planning and logical thinking to ensure that all individuals reach the other side without any harm.