Transcript for A New Threat to Wildlife in 'The Pearl of Africa'
We're about did take you on a spectacular journey deep into the heart of Africa where one national park is grounds for fierce battles. Not just between predators likely ons and their prey. There are oil companies with their own plans for the natural paradise. While many are optimistic there are still those who fear the park's possible ruin. Here's ABC's Gloria Riviera. Reporter: This corner of northern Uganda, where the river nile cuts through lush rain forest and golden Savannah, is known as the pearl of Africa. A nickname proudly reclaimed by mercy falls national park even after decades embroiled in environmental crisis. It's been a long seven-hour car ride across two continents. It is not an easy place to get to. But on the horizon, a creeping new challenge. One that again threatens the park and its wildlife. Clouding its future in uncertainty. Are you excited to be here? Very excited. Reporter: We've traveled here with shabani. I'm resting up to be excited. We're seeing the nile. It's amazing to see the nile. Reporter: She's a wild-expert and national geographic explorer born and raised in neighboring Kenya. Yeah, there they are, coming out of the water. Rrr! We're speaking hippo. Reporter: She's helping explore how this delicate ecosystem is returning from the brink. You're jumping out of your skin to get out. Reporter: Despite the wait she isn't disappointed. A special sighting right away. These are endangered. Reporter: The rare Rothschild giraf giraffe. There's only about 1,000 left in the world. Reporter: Just one of the many vulnerable species that calls this home, including the elusive specialty, the african lion. Our guide George says this area is known to be a breeding ground for big cats. That's what we're looking for. It's like looking for a needle in a hay stack. Literally, lions can be anywhere in this bush. Reporter: After scanning our surroundings, George spots what we're looking for. There, there, there he is, there he is, yeah. Reporter: Two lions napping in the shade. Took to the left. Reporter: Much more interested in his companion. They seek out some privacy in the tall grass. They can mate every 20 to 40 minutes when they're in peak time for mating. She looks exhausted. He's done. This is as good as it gets. Reporter: This pairing and the cub it may produce points to a bright future here when it was almost lost forever. During the brutal and violent reign of former president id idi amin, the park became lawless. Hippos and buffaloes, up to 95% was lost. 95% during that time? Lost due to poaching. Due to poaching? Reporter: He saw it firsthand. He now manages the national park for the Ugandan wildlife authority. Oh my lord. Look at this. This is just -- this is a container full of poaching equipment. Put it on the neck, squeeze like a hangman. This is like a land mine. Reporter: Since Tom took over things have started to change. Two years ago, we were getting when one patrolman would come back with 50. 50? But now you can come back with none. That means the anti-poaching efforts is paying off. Reporter: In part with the support of groups like the Uganda conservation foundation. We've managed to get rid of over 8,000 snares in one year. Reporter: Michael works closely with the uwa to ensure pictures like these, filmed by national geographic for a special about the nile, images of elephants and lions caught in snares, become a thing of the past. After 30, 40 years of real trouble, I mean, you really can't get much more trouble than the idi amin era then Joseph coney, is now recovering. It's one of the most spectacular, heartwarming stories. Reporter: Driving through the park today this troubled past is nearly invisible. Signs of a future threat are hidden in plain sight. There are oil wells in this park? Yeah. Reporter: The promise of a fortune. Locked underground, drawing major international oil companies to the region. What we're seeing here, pristine, untouched park, could change dramatically? We don't know. Maybe. They are promising that they will do their best to make sure that the impact is minimized. This is how it looks at the moment. Reporter: Most of the construction in the park, so far just for oil exploration, has been temporarily restored. We are looking at one of the tracks leading to the wells. You can tell because all of those plants are sort of in rows. Exactly. If you can see that behind me, there's a darker patch of grass over there. And that's where they've done some exploratory drilling for oil. Reporter: When development moves ahead as planned, the wells will be impossible to conceal and the environmental impact impossible to predict. When you first heard that oil exploration would be done in the park, what was your reaction? I think I was like, oh my god. I thought it was probably some -- it was going to be very bad. Reporter: Those fears have faded, replaced by optimism. You think the two, conservation and oil, can coexist? We want it to coexist. We want it -- we are doing everything possible to make it coexist. It's a paradise we have to take very good care of. Reporter: A message echoed in the corporate videos of the oil joint. This is a big budget. The expenditure will be the size of the gdp of the country. Reporter: Promising careful oversight and very real potential for the local economy. Once we go in we need to ensure that we have left the environment pretty much the way that we saw it in the first place. Reporter: But he believes the oil companies should leave the park not just as they found it but better off. The challenge is, can we get those companies and the government to get that to happen? I've not seen evidence of it yet. Reporter: A discovery that could be Uganda's economic salvation or some fear its ecological ruin. Either way the stakes couldn't be higher. You want your grandchildren to have the most incredible opportunity one day to go and see one of the most staggeringly beautiful countries in the world. We must save it. Reporter: For "Nightline," Gloria Riviera in Murchison falls. "Destination" wild, Sunday nights on nat geo wild.
This transcript has been automatically generated and may not be 100% accurate.