The authors describe several methods of preserving waterlogged wood used by Swiss archaeologists since the 19th century to treat finds from lakeside settlements. Large dugout canoes discovered in the second half of the 19th century were unsuccessfully treated with natural substances such as beeswax, linseed oil, resins or glues. Procedures employed in the first half of the 20th century which also gave unsatisfactory results included slow drying, preservation in a liquid, dehydration, impregnation, protective coatings, and treatment with alum. The principal methods tested in Switzerland over the last two decades described here include alcohol-ether-resin, Arigal C, Lyofix, PEG and freeze-drying (of which a successful experiment is detailed). Specialized laboratories have undertaken in-situ polymerisation treatments and systematic dendrochronological studies (project 16 of the National Fund for Scientific Research) recorded in a computerized data bank.