Liquefied natural gas is stored, for example, on board ship, in a battery 2 of storage tanks 4, 6, 8 and 10. Submerged pumps 16 are used to transfer the LNG to secondary storage vessel 22. The pressure of the LNG is raised and it is transferred from the secondary vessel 22 to a forced vaporiser 36, in which it is vaporised. The outlet pressure of each submerged pump 16 may be relatively low and the apparatus may be operated either intermittently or continuously.