The volcano-triggered disaster struck at night and without warning, sweeping over popular beaches on southern Sumatra and western Java and inundating tourist hotels and coastal settlements.
While tsunamis are often triggered by earthquakes, in this case experts believe the deadly waves were generated by an eruption of the Anak (or "child of") Krakatoa volcano, which could have caused a large undersea landslide or flow of molten rock into the water.
According to Richard Teeuw, a disaster risk reduction expert at the University of Portsmouth in England, the likelihood of further tsunamis in the Sunda Strait will remain high while Anak Krakatoa volcano is going through its current active phase as it could trigger further submarine landslides.
Fearing another tsunami, many of the more than 5,000 evacuees have been too afraid to return home.
"I've been here three days," said Neng Sumarni, 40, who was sleeping with her three children and husband on the school's floor of her village, Sumber Jaya, located near the popular beaches of Sumatra. "I'm scared because my home is right near the beach."
Fears of a public health crisis
As desperately-needed aid flowed in Tuesday, humanitarian workers warned that clean water and medicine supplies were dwindling, as people crammed into shelters.
Meanwhile, rescue teams were using their bare hands, diggers and other heavy equipment to haul debris from the stricken area and hunt for corpses, as hopes of finding more survivors dwindle.
The tsunami was Indonesia's third major natural disaster in six months, following a series of powerful earthquakes on the island of Lombok in July and August and a quake-tsunami in September that killed around 2,200 people in Palu on Sulawesi.
The vast archipelago nation is one of the most disaster-hit nations on Earth due to its position straddling the so-called Pacific Ring of Fire, where tectonic plates collide.