High resolution transmission electron microscopy (HRTEM) has been used to investigate the extended defects induced by the interaction between hydrogen and silicon during the high temperature annealing process in the hydrogen-implanted (111) silicon wafer. It has been found that the high temperature annealing process, like the low temperature annealing process, leads to the formation of cracks. However, beneath the cracks induced by high temperature annealing, there appear many additional dislocations. Some amorphous bands have also been observed. In addition, a string of cavities, which are truncated octahedral in shape and surrounded by {111} and {100 } lattice planes, have been revealed. These cavities, some of which have amorphous inner walls, are arrayed parallel to the top surface. Between cavities, there normally appears a dislocation band.