Below you have a chart to help you decide when you might wish to visit.
Back in 1955 -59 a Dr. Archie Carr from University of Florida wanted to protect the area. Due to his work Costa Rica now has the Tortuguero National Park. This area is well protected today. To see the turtles hatching at night you must have a trained guide. Cost about $10 – $20 depending on a number of factors.
You can drive to Tortuguero, the below map gives you an idea. From my home to Tortuguero it is about 4 hours. (A to B) From San Jose the capital about 4 to 5 hours. There are toll roads as you leave the capital, San Jose.
If you drive to the area of Tortuguero, when you arrive you will still need to take a boat taxi over to the actual town of Tortuguero to visit the national park.