The heaviest venomous snake is probably the eastern diamondback rattlesnake (Crotalus adamanteus) of sparse woodland and lowland coastal regions in the southeastern United States. It averages 5.5-6.8Kg (12-15lb) and 1.52-1.83m (5-6ft) in length. The heaviest on record weighed 15Kg (34lb) and was 2.36m (7ft 9in) long.
The gaboon viper (Bitis gabonica) of tropical Africa is probably bulkier than the eastern diamond, but its average length is only 1.22-1.52m (4-5ft). An exceptionally long 1.83m (6ft) female weighed 11.34Kg (25lb) and another female measuring 1.74m (5ft 8.5in) weighed 8.2Kg (18lb) with an empty stomach.