I read cozy and historical mysteries, a bit of Paranormal/UF, and to mix it up, I read science and gardening books on occasion.
I've finished Part II and Humboldt has finished his 5 year tour of South America, with a brief stop in the newly formed US to meet Thomas Jefferson, a fellow avid naturalist. He also shared with Jefferson all his observations about Mexico, with whom the US was in the midst of a border dispute at the time. Nothing like a little innocent political intelligence to cement a friendship.
The trip through the Amazon, while recounted vividly, was also recounted relatively briefly. Wulf mentions Humboldt and Bonpland suffering a couple of fevers and generally supporting entire populations of mosquitoes, but doesn't dwell for very long on any one aspect. This worked for me, especially when the subject of animal specimen collections came up - those parts of the book where I had to do the reading equivalent of putting my hands over my ears and loudly 'la-la-la'-ing my way through.
Section III has Humboldt returning to Europe and sorting through 5 years of finds. This will be either really interesting, or coma-inducing. The previous 8 chapters indicate it will, thankfully, be the former rather than the latter.