The International Date Line can cause confusion among airline travelers. The most problematic situation usually occurs with short journeys from west to east. To travel from Tonga to Samoa by air, for example, takes about two hours but involves crossing the International Date Line, causing passengers to arrive the day before they left. This often causes confusion in travel schedules, like hotel bookings. Some examples of time zone adjustments for real air trips are: Alaska-Siberia 21 hours, New Zealand-Cook Islands 22 hours, and Samoa-Tonga 24 hours.