Clipper ships traveled at blistering speeds but conditions on board were brutal, and opium was their most profitable cargo. https://www.nationalgeographic.com/science/article/news-clipper-ship-opium-trade-gold-rush
How Opium Merchants Used Bankers, and Vice Versa American Merchants and the China Opium Trade, 1800-1840 https://quixoticjoust.blogspot.com/2013/12/how-opium-merchants-used-bankers-and.html