Jallah Faciann, from the U.N. High Commission for Refugees (UNHCR) darts in and out of the rows with a bundle of red bands. Working quickly, he fastens the plastic strips around people's wrists as the crowd begins to swell and lunge toward him.
"Each day we have 600 to 900 people traveling," he explains. "But there's a huge fight to board normally, because people just want to get out of here."
There are still upwards of 30,000 refugees in Kagunga, which was once a quiet Tanzanian fishing village on Lake Tanganyika.
When Burundi's President Pierre Nkurunziza announced he would run for what many see as an unconstitutional third term, sparking a wave of violent protests, this isolated little stretch of sand and rock ringed by mountains became something entirely different: a haven for thousands of Burudians fleeing their country from as far away as Bujumbura.
While a coup attempt has been scuttled, protests continue on the streets of Burundi's capital each day -- and fears of further violence remain.
Francine Niyongere remembers Burundi's very recent 12-year civil war -- in which 300,000 were killed and violence spread along ethnic lines -- only too well: "I saw then that anyone could be targeted, so this time around, I didn't wait."
Around 80% of these refugees have been here before. For them, it seems better to live in the most miserable of conditions than risk the turmoil at home, caused by Nkurinziza's determination to maintain his grip on power.
"What can I tell him?" Niyongere asks with a wry smile. "He's been told a few times what to do and he still hasn't listened."
UNHCR says they are slowly turning the corner. Just weeks ago there were no tents, few toilets and not enough treated water. It's an equation that terrified UNHCR's Amah Assiama-Hillgartner.
"This was like a nightmare," she says. "And until now it looked like it was going no where."
Aid workers here are hesitant to utter the word cholera -- partly because of the strict protocols: it's up to the Tanzanian Ministry of Health to formally announce an outbreak; but also because they know all too well what the disease brings in crowded conditions like this.
So far more than a dozen have died from complications of watery diarrhea, a not-too-euphemistic name for the disease's main symptom.
Call it what you want, the threat of an outbreak has UNHCR, the Tanzanian government and other agencies in emergency mode.
Their goal is to move all of the refugees away from Kagunga and transfer them to the country's largest refugee camp, Nyarusugu.
That task has fallen on the MV Liemba. The old First World War gunship of Lake Tanganyika is now tasked with moving refugees from Kagunga as quickly as possible, in two boatloads a day.
Above deck, children play and women sing, relieved to have left Kagunga. Below decks, though, it's a different story, with IVs hung from the ceiling, as doctors try to rehydrate patients.
"We did what we weren't supposed to do," says Dr. P. Njogu. "You're meant to treat the outbreak where it happens, but if we did that we'd be counting deaths in terms of thousands.
"When it comes to saving lives, it's not a question of rules: It's time to break the rules."
Just the night before a pregnant woman had died from complications of cholera at the Kigoma refugee transit center. She'd made it out of Burundi, away from Kagunga, but the journey to safety proved too long to make.
"It's a double tragedy," said Dr. Njogu.