Van Koolwijk had no formal education in
archaeology, but he showed great passion as an observer and fieldworker. His fascination with
Amerindian history led him to conduct the initial archaeological explorations on Aruba, Bonaire, and Curaçao, making him the pioneering archaeologist of the
Dutch Caribbean. In recognition of this accomplishment, he was appointed as a knight in the
Order of the Dutch Lion in 1887. In 1875, Van Koolwijk created sketches of the rock paintings found in the Onima Caves near
Rincon. These sketches marked the first recorded documentation of the prehistoric rock paintings in Bonaire. Alongside caves, rock drawings can also be seen on the ceilings of wave-cut platforms and on the shaded side of diorite blocks in Bonaire. In 1907, Paul Euwens published these sketches, referring to them as '
hieroglyphs'. Van Koolwijk also conducted research on
pictograms in Curaçao and Aruba. During his time in Curaçao, he discovered various prehistoric settlements on the island, including the village of Ascension. His most significant find was the village of San Juan, situated on the western coastal terrace of Knip in
Bandabou. Additionally, Van Koolwijk amassed an extensive collection of shells and crustaceans, carefully documenting their precise locations. (formerly the Rijks Ethnographisch Museum) in
Leiden|left On the island of Aruba, Van Koolwijk conducted research at the Indian camp located in
Santa Cruz. He also explored other sites in
Fontein,
Savaneta,
Tanki Flip, and
Arikok. During his investigations, he collected materials found on the surface and conducted small excavations to study remnants from the pre-Columbian era. The discoveries included pottery shards, stone tools, human skulls, and large burial
urns containing bodies in a crouched position. These findings provided evidence that the Carib people had also inhabited Aruba prior to the
Arawaks, who were the inhabitants when the Spanish explorers discovered the island. In 1923, the excavations in Santa Cruz and San Juan were continued by Jan Petrus Benjamin de Josselin de Jong, an anthropologist and curator at the .
Collection Van Koolwijk During the years 1883, 1885, 1886, and 1887, Van Koolwijk generously donated the data and materials he had gathered to the Rijks Ethnographisch Museum in
Leiden. These valuable contributions are now recognized as the
Van Koolwijk Collection. In 1885, more than 120
ethnographic objects were generously donated, and a detailed list of these items was published in the Nederlandsche Staatscourant on September 16, 1885. Since the
National Archaeological Museum Aruba opened its doors in 2009, five remarkable artifacts have been loaned to the museum, including three exceptional pieces—a beautifully adorned calabash, a ceramic face jug, and a ceramic figurine. Additionally, Van Koolwijk's contributions can be found in various other institutions, such as the (numismatic museum), the
Rijksmuseum van Natuurlijke Historie (National Museum of Natural History), the
National Museum of Geology and Mineralogy, the , and the
Hortus Botanicus Leiden. == Photography ==