Day visit from Guayaquil:

Possible, but a long day.

Driving time from Guayaquil:

More or less 4 hours per way.

What is it?

It is a unique state-managed park, and perhaps the third biggest deposit from petrified wood in the world, where you still see living trees in it. Visited by famous scientists such as Theodor Wolf and 
Eugene Shoemaker, it might be one of those places worth the drive, or on route between Loja and Machala, or Guayaquil. The only missing things are the dinosaurs.

What can you do there?

Hiking, sightseeing.

Possible / Suggested Overnight Town:

Machala, Guayaquil, Zaruma.