The thickest tree trunk is found in the Amazon rainforest. The Amazon rainforest is home to some of the largest trees in the world, including the kapok tree (Ceiba pentandra), which can reach a height of over 200 feet and a diameter of 12 feet. Other large trees in the Amazon include the mahogany tree (Swietenia macrophylla), which can reach a height of 150 feet and a diameter of 6 feet, and the Brazil nut tree (Bertholletia excelsa), which can reach a height of 100 feet and a diameter of 4 feet.