Pakistani authorities are struggling to stop their biggest lake from bursting its banks after last-ditch attempts to lower water levels failed.
Manchar Lake, in Sindh province, is dangerously full after record monsoons that inundated a third of Pakistan.
Three breaches of the lake's banks so far - two to protect areas nearby - have displaced over 100,000 people.
But it could still overflow and rescue teams are racing to evacuate many more people who remain at risk of drowning.
Floods in Pakistan have affected some 33 million people and killed at least 1,314, including 458 children, Pakistan's National Disaster Management Agency said.
Estimates suggest the floods have caused at least $10bn (£8.5bn) of damage.
Sindh province produces half of the country's food supply, exacerbating fears of serious food shortages in a country already struggling with an economic crisis.