Monterrico is a pretty sleepy costal Pacific beach town, about a 2 1/2 hour drive from Antigua by shuttle bus. Although it seemed pretty off-the-beaten-track at the time of writing for the usual tourist, there is definitely enough going on for a day-trip from Antigua, or for an overnight in town. We chose the day-trip option; as of Jan. 2009, shuttles leave Antigua at 8AM ($10-12 US O/W), and leave Monterrico at 4PM (60Q, ~$7.5 US O/W). Do not buy the round-trip in Antigua, as you can get it cheaper in Monterrico from at least two sources; also check on the schedule, as we went on a Saturday. You'll get a bit better rate with USD than with Quetzals in Antigua.
Once in town, you'll notice how much the surroundings have changed; descending from 1500m to sea level makes quite a difference in the flora and fauna. The beach is known for turtles, but unfortunately the season in January isn't correct; as a consequence, while we were there we saw very very few tourists. The Tortugario Monterrico Visitor's Center was interesting for its live turtles, crocodiles, and iguanas, although the new prices - 40Q for tourists - makes it a bit expensive for its content. See if you can get in for the Guatemalan 10Q price, however.
At the Tortugario, it is definitely worth booking a boat tour of the mangrove forest. It is a very reasonable price - 50Q per person - and is much more worthwhile. The Tortugario staff will deliver you to a very well trained villager who will take you and/or a friend around the mangrove forest for about an hour and a half and explain the surroundings (though in Spanish only). Bring sunblock! The mangroves held a contrast I found quite fascinating. On one hand, passing by every ten minutes or so were mini-barges dragging the cars of the Guatemalan wealthy from La Avellana to Monterrico. On the other was the village of Agua Dulce, a place two kilometers deep in the mangroves, accessible only by boat and with no electricity or fresh water.
Finally, the beach is a must-see. Although it admittedly is not the nicest beach, it is a black-sand beach of volcanic origin, perfect for sunbathing. The Pacific becomes deep quickly, but is the warmest water I have been in, at least compared to beaches in the Caribbean, Hawaiian, Northern Asian and Northern American coasts.
Cost: 370Q, including transportation, Tortugario admission and tour, beach, beach snacks and water, and lunch.
Note: Pictures courtesy D. A
Monterrico beach entrance
Black sand beach looking north