Binoculars are great to have in Arenal (Fortuna)
Like I normally suggest, pack as light as possible. My general rule is to pack 1/3 less the amount of clothes you think you need and 1/3 more the amount of money you think you need. You should have some comfortable walking shoes, but hiking boots are not really necessary for visiting Arenal Nat'l Park. Sturdy sandals are good to have too. Basic stuff, a mini med kit is always great to have. CAMERA! and lots of film. BINOCULARS were the best plus to have! You can see the rim of the volcano up close and see lava comming out, especially at night!
Lookin' for some animals
On the way from San Jose to Arenal there are several animal centers where you can look out for hummingbirds (colibríes), parrots, macaws, iguanas, tarantulas, and horn beetles.
Hre are the facts:
Costa Rica is internationally recognized for its efforts to ensure biodiversity and protect natural resources. The country boasts 230 different protected areas (about 28% of the country), ranging from completely protected reserves to national parks where research, tourism and controlled development and extraction are permitted. The cloud forests, rainforests, volcanoes and mountain plains here are thought to shelter more than 6,000 plant species, including at least 1,000 orchid varieties alone. The presence of over 500 species of butterflies has led to profitable "butterfly ranching" while more than 800 bird species--quetzals, toucans, hummingbirds, scarlet macaws--are found in the wet and dry forests. The magnificent beaches bordering both coasts are among the world's largest-known nesting grounds for sea turtles.
I can't remember the name of the village, but on the bus ride to the Rio Frio, the driver stopped to let tourists see the large number of iguanas that hang around in the trees there. Not long ago, an iguana made for a fine meal, tasting something like chicken, but now this practice is discouraged in favor of tourism related use of the animals. What was remarkable for us was not only how many iguanas hung around, but how close we could get to them. These were very large and old iguanas that napped on porches and in the trees.
Baldi Hot Springs
Baldi is the budget alternative of Tabacon. It is less fancy in terms of the pool design but it has the same hot springs source as Tabacon. There is a swim up bar, and about 10 other hot spring pools with different water temperature. If all you care is getting a hot spring soak, Baldi is a good choice, which is more than half the admission price as Tabacon. You don't have to bring your own towel as they provide one to you with a 100% refundable deposit.
There is a bar and restaurant. But they are quite pricey compared to places in town.
Many tour companies package the hot spring soak with other tours, such as the volcano hike and the walk to the waterfall. That's how most ppl get into the hot springs. If you're not interested in the tour, you can also buy tickets (with free shuttle service) from these companies, as well as from the hotels. Shop around to find the best deals.
The majestic Lake Arenal near the Arenal Volcano is the largest in Costa Rica. I hadn't realized it was so large but we drove around it for a couple of hours on our way to Liberia. It's very scenic with rolling hills and of course the volcano. The lake is known for its bass fishing.