The multitude on the "other side"must have been near the northeast shore where Jesus had fed the 5,000 south of Bethsaida. They were across the lake from the northwestern shore where Jesus and the disciples now were, in Capernaum. They could not figure out where Jesus could have gone. The disciples had left in one boat without Jesus. There was only one other boat still there. Jesus had not used it to leave the area. While they waited for Jesus to appear, other boats with people from Tiberias, on the western shore, arrived. Eventually the crowd realized that Jesus was not in that region, so they boarded the boats that had come from Tiberias and set out for Capernaum. They probably thought they could find Jesus there because Capernaum was His headquarters. When they did find Him, they wanted to discover how He got there.
Why did John bother to relate this seemingly unimportant information? Apparently he did so to document the fact that Jesus really had crossed the lake by walking on the water. Another reason could be that his description supports Jesus' statement that the people sought Him (v. 26). In view of what these people proceeded to demand of Jesus (vv. 30-31) it was important that John show that they were the very people who had witnessed the sign of the miraculous feeding.
