We had a divine Christmas Day ride with Marvin and the happy, well-kept horses that he calls his "boys". He is extremely knowledgeable about the local flora and fauna, kept all four of us (Ages 10-74) safely and happily on our horses, and showed us terrain that we wouldn't have seen otherwise. He is funny and engaging, and we all had a blast.
In comparison to the other outfittes in Montezuma, Marvin shines. The two other Montezuma outfitters do NOT take good care of their horses, who are often visibly exhausted, lame and dispirited. Last year, there were two deaths among their number. Truthfully, a ride up the Montezuma beach to the waterfall sounds fun, but it's a long, hot trudge with little change in scenery and VERY hard on the horses with the sloped terrain and unsure footing.
In addition to the rainforest options, Marvin will arrange sunset rides in Malpais, if you want a more satisfying experience. Transportation to his stable in nearby Cabuya is easily procured and the 15-min coastal drive is lovely. In Cabuya, the bakery there is FANTASTIC for lunch or tea.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.