Congratulations, you are getting closer to paradise! When you arrive in Chiquilá, you must head towards the pier. It is about 3 minutes walk. Once there, you have two options to get to Holbox:
There are only two ferry companies that make the trip to the island: “3 brothers” (blue color) and “Holbox Express” (red color).
The second option to arrive is through a fishing boat. You will be charged exactly the same as the ferry, that is USD 8 to the island (one way). The benefit is that they do not handle strict schedules so it can be a good option if you did not get to take the ferry.
Both options are good and cost the same. You just have to consider that the boat trip is a bit more "adventure" because it hits harder with the waves. On the ferry, you can relax more, sunbathe up or be air conditioned inside.