If you’re taking a high-demand bus route, like Cancun to Tulum, or traveling during the holidays, like Spring Break in April, you should definitely book your bus in advance. Most buses are completely sold out during holidays, so you will have to wait a few days for an open seat if you wait until the last minute to book. Either way, it’s a good idea to buy your tickets ahead of time to avoid waiting in the ticket line at the station or risk not getting a seat on the bus.