The first area I visited during my trip to this amazing country in July/August 2017 was the Caribbean lowland rainforest near the border with Nicaragua.
I was staying in an area known locally as Boca Tapada; located nearby the mouth of the San Carlos River. It is off-the-beaten-track from most tourist itineraries and because of this the wildlife viewing opportunities are second to none.
I stayed at an eco-lodge called Laguna del Lagarto. It is a haven for many bird species but in particular Toucans, Vultures and Macaws. By attracting key species - for example ecologists consider toucans among the most important seed dispersers in the rainforest - this in turn provides a platform for smaller species, such as Red-Legged Honeycreepers, to thrive.