In good years, more than a hundred thousand tourists flock to this marine park on Costa Rica's Pacific coast to see humpback whales breaching in the blue waters.
But warming temperatures - driven by climate change and strengthening El Nino events - are beginning to threaten the region's tourism economy.
"When temperatures rise two or three degrees (Celsius) above the region's average, we have very few whale sightings compared to normal years," said whale specialist Jose David Palacios, who works at the Marino Ballena National Park with the Keto Foundation, a Costa Rican marine conservation organisation.
"Typically, there are many sightings a day. When temperatures rise, there are only one or two a week," he said.
For Julio Badilla, the operator of Dolphin Tours, that's bad news. Over the three most recent tour seasons, including a strong 2015-2016 El Nino period, whale sightings have been "terrible", he said.
Whales are one of the main tourist draws for Marino Ballena National Park, one of Costa Rica's most visited natural areas. As climate change hits the country's parks and biodiversity, it is also threatening local economies highly dependent on tourism, scientists and local people say.
"What's happening with the whales is concerning. In previous years (2015-2016) there was a decrease in the amount of tours precisely because the probability of finding whales was very low," said Rafael Sanchez, a tour operator from the company Adventure Bay.
Scientists similarly have noticed a drop in whale sightings in the park, mainly in warmer-than-average years, they said.
Although more study is needed, they believe rising water temperatures may be altering the migration routes of humpback whales moving past Costa Rica from the north.
When the whales descend in search of warmer waters to reproduce, they may now be finding them before reaching the park, scientists believe. The problem is that, as the whales spend time elsewhere, the community of Bahia Ballena could see its income dry up.
"Whale sighting tourism really moves this community. Tourism has been the main economic activity in the region for a couple of years now. Recently, it's been growing in these type of activities," said Sanchez, the tour operator.
A study published in the journal Nature in 2014 estimated that extreme El Nino events, like the recent one in Costa Rica, will become twice as likely due to climate change.
That is a growing worry for tour operators in Bahia Ballena.
Along with altering whale migration, climate change is causing other problems as well, from coral bleaching to rising sea level, Palacios said.
A drop in tourism in the region would mean a big hit for Costa Rica's tourism economy. According to data from the Costa Rican Institute of Tourism, the park is the third most visited in the country with over 130,000 tourists per year.