As leader, Lorentz aimed to reach the snow-capped peaks of the central highlands from the south coast. Though he failed to reach the summit, he successfully collected significant biological and ethnographic data.
After returning from New Guinea, he attempted to synthesize his observations into a comprehensive work on the flora of the island, but he struggled with the sheer volume of material and his declining health. Many of the specimens he collected were analyzed by other botanists, and numerous species were named in his honor, including the genus Lorentzia .
Lorentz first traveled to the Dutch East Indies in 1903 as a member of the North New Guinea Expedition. The goal was to explore the northern coastal regions. During this journey, Lorentz became fascinated by the complex interplay between geological processes and plant distribution. He suffered a severe attack of malaria during this trip, a common hazard for explorers in the region, which temporarily halted his work but did not deter his resolve to return.