The Schonenberg was on a homeward-bound journey from Batavia with a general cargo, including porcelain and peppercorns, when she ran aground on the reef off Northumberland Point.

The Schonenberg departed from Batavia for the Netherlands on September 26, 1722. Upon arriving at Cape Agulhas, South Africa, she ran aground on a reef near Northumberland Point. Skipper Van Soest was later suspected of intentionally running his ship aground. An attestation (statement) in the Amsterdam Archives at least supports the suspicion.

One of the boys on board was Dirk de Vries (17 years old in 1724). He was Skipper Van Soest's personal servant and witnessed the skipper's actions immediately after the ship ran aground. According to De Vries, the skipper had taken a small package, which had been stored in a lead box (in a lectern) in the skipper's cabin, out of the box and put it in his own pocket.

Part of the cargo to the Cape
After the grounding, a messenger was sent to the Cape Colony. The cargo was removed from the ship as much as possible. Eighteen men and the skipper stayed behind for this. After two months, three carts arrived from the Cape that took part of the cargo back to the Cape Colony.

However, a large amount remained behind in the ship. Subsequently, the skipper returned to the ship three weeks later with five carts and 12 sailors (including the witness, who was still on board), who were also loaded up. One of the five carts was loaded with ammunition. Then, the empty ship was set on fire.

Part of the cargo disappeared
And so they set off again for the Cape. A halt was made 12 miles before the Cape at the homestead of a certain Jacob van der Heijde. The four carts with valuable cargo were unloaded there. Only the wagon with the ammunition remained untouched. The valuable cargo was taken away and was never seen again.

The accident cost no lives, and all one hundred people on board managed to reach land safely. Things did not end well for the cargo and the valuable diamonds on board.

Aftermath
Skipper van Soest was dismissed from his position as skipper and departed for Europe on an English ship. Part of the cargo and crew also sailed to England. In England, witness de Vries saw a small walnut chest resurface: "with stones the size of peas." These diamonds eventually arrived in Amsterdam with the skipper.

This is an example of smuggling, tampering with the cargo, and concealing the valuable secret extra cargo (diamonds) that the skipper was able to pocket due to the disaster, despite the strict rules and controls of the VOC.

Some of the remains from the Schonenberg, which include ceramics and cannons, are kept at the Shipwreck Museum in Bredasdorp. The site was worked on by J Herbert, who wrote a book on the Schonenberg.

• Bruijn et al. (eds).
  DAS 6541.2.
• Dagregister Kaap , 24-11-1722.
• La Grange, L., Williams, B.L., Gribble, J. Manders, M.R., Derksen, L.F., Brouwers, (2024).
  Dutch Shipwrecks in South African Waters: A Brief History of Sites, Stores and Archives.
  SAHRA.
• pp 420-423.
  Stadsarchief Amsterdam.
  5075.
  9074.