"It was mind-blowing," he told reporters in Portugal where he was taking part in the Laureus World Sports awards in Estoril, a resort outside of Lisbon.
"I was there only 18 months ago with England and staying in the Galle area in a beach house with six other commentators. But when I returned, that house was totally gone after being hit by the tsunami with 30 feet (nine metres) of water travelling at around 300 miles per hour (480 kilometres per hour)."
Botham, 48, visited several villages ravaged by the December 26 tsunamis as well as the Galle International Cricket Stadium south of Colombo as an ambassador for a British charity helping victims of the disaster.
"The stands at the Galle Cricket Ground have been ripped apart, houses have been levelled and there has been a total breakdown of infrastructure," he said on Monday.
"You now have villages just 200 yards (metres) apart from each other but without any communication between them," he added.
Galle was one of the worst areas hit by the tsunami that left at least 31,000 people dead in Sri Lanka.
Botham was one of the finest all-rounders of his time with 5,200 Test runs and 383 wickets until his retirement in 1992.
He was awarded the Order of the British Empire that year and currently works as a popular television commentator.