JAKARTA - The tsunami came while fisherman Ari Agus Arman Harianto was out at sea, crushing the boat he was in.

For an entire day, the 24-year-old clung to the rubble of his ruined fishing boat to stay afloat. He later managed to paddle his way to nearby Pulau Panjang - a small island close to the rumbling Anak Krakatau, which triggered the deadly Sunda Strait tsunami that struck in the evening of Dec 22.

Indonesian navy officers on Sunday night (Dec 30) rescued the fisherman when one of its ships came across him while surveying the condition of Anak Krakatau.

He was in stable but weak condition after a week spent foraging for food while lost on the island - eating even the seeds of the ketapang tree.

"There, I ate whatever could be eaten," Mr Agus, who is from Lampung, told local media at a port in Banten on Monday (Dec 31), still pale from his ordeal.

A section of Anak Krakatau's slope collapsed after it erupted on Dec 22, sliding into the sea and displacing massive amounts of water that sent waves up to 5m high sweeping up coastlines.

More than 430 people have been killed, and over 14,000 injured.

On Sunday, Indonesian authorities said the eruption of Anak Krakatau had stopped.

Seismographic data from Sertung Islands, a cluster of islands near Anak Krakatau in the Sunda Strait, show that there were no more unusual tremors in the volcano, with the average amplitude of volcanic activity standing at 10mm, the Volcanology and Geological Disaster Mitigation Centre (PVMBG) said in a statement.

Anak Krakatau's average amplitude during an eruption is 25mm to 30mm.

The volcano - whose name means Child of Krakatoa - lies in the Sunda Strait that separates Java and Sumatra islands.