A pressure and temperature core sampler comprises a tool for recovering cores specifically enabling the evaluation of methane hydrate resources. Because methane hydrate tends to decompose under conditions of pressure decrease and/or temperature increase as the samples are retrieved to the surface, a coring tool in accordance with the present invention provides a self-contained system for retrieving core samples at or near in situ pressure while cooling the core sample. The coring tool is preferably a wire line retrievable device that provides for nearly continuous coring during the drilling operation.