According to Official Guinness Records,
The first and only circumnavigation by an amphibious vehicle was by Ben Carlin (Australia) in a modified Ford GPA amphibious jeep called Half-Safe. He completed the last leg of the Atlantic crossing (the English Channel) on 24 August 1951. He arrived back in Montreal, Canada on 8 May 1958, having completed a circumnavigation of 62,765 km (39,000 miles) over land and 15,450 km (9,600 miles) by sea and river. He was accompanied on the transatlantic stage by his ex-wife Elinore (USA) and on the long trans-Pacific stage (Tokyo to Anchorage, Alaska) by Boye Lafayette De Mente (USA).Carlin died 7 March 1981
For a complete list of 1958 records, please visit 1958 Guinness Records in Australia.