In 1770 Lieutenant James Cook who discovered the east coast of Australia had to jettison iron cannon and carriages along with iron and stone ballast when the Endeavour struck a coral reef. These relics were recovered in 1969 and their condition and properties after almost 200 years under the sea are discussed. The treatments used to stabilize the iron cannon and carriage remains are then detailed. These include electrolytic reduction followed by washing in inhibited distilled water before a final wax impregnation, also treatment in an activated molten caustic soda bath followed by heat treatment before wax impregnation. The historical aspects of the relics with regard to their authentication are also mentioned.