One of the final journeys was to Atsj, a hub of some 1,500 people located about 35 miles from their base in Agats.
Author Toohey wrote that the trip began auspiciously when police official Henri Watrin declared the boat overloaded, weighed down with axes, machetes, knives, tobacco and fishing line and hooks for bartering, as well as clothing, water, food and fuel.
Watrin told Toohey, "I said to him, 'Michael, you can't go with that boat. I forbid you. You have to unload it, you have to lighten it up or you don't go at all.'
"So he said, 'Yes, yes, yes, I'll unload it.'"
But when the constable left, Michael pushed off — with the boat still overloaded — at noon on Saturday, Nov. 18, 1961.
On board were Wassink, Rockefeller and two Asmat teens, Simon and Leo.
Wassink would later say that Simon and Leo urged the westerners to speed the boat along the coast past the mouth of the Eilanden River, with its predictably violent tidal surge.
Yet the boat tarried along.
At 2:15 p.m., as the boat entered the water where the Eilanden flowed into the Arafura Sea, "something terrible happened," Wassink would later say.
"A following wave came over the stern and side of the boat, stopping the engine and swamping the hulls," he told the Dutch press. "We sank visibly in the water, and the current continued to push us out to sea. Simon and Leo were afraid and said they would like to swim for shore. We gave our permission, of course. They each took a jerrican, emptied the gasoline out of it and jumped into the sea using the cans as life buoys. As they left us, I asked them to try to get help from someone on shore. They promised they would."
Rockefeller was a strong, confident swimmer. But Wassink was not, and he announced that he intended to stay with the boat and await rescuers. Rockefeller likely would have joined the Asmat teens in their dash to shore but probably felt obliged to stay with Wassink.
Meanwhile, the low-riding boat continued to drift farther out to sea, pushed by the Eilanden's tidal flow. Not long before dark, a rogue wave capsized the rig completely, and Rockefeller and Wassink found themselves clinging to the hull. All their food and water gurgled to the bottom of the sea.
"We realized our situation was precarious, but we weren't panicked," Wassink said. "We had hopes that Simon and Leo would be able to find help before out situation worsened. But we were soaking wet and very cold as the sun began to go down in the afternoon."
They spent a sleepless night adrift.