Lock Chests are containters that first appeared in numerous realms in Spyro the Dragon. Each chest contains many gems, and can only be opened with a single corresponding key hidden somewhere else in the realm. It appears that Gnasty Gnorc put some of the Dragons' stolen treasure in these chests in an attempt to keep it from being recovered, but Spyro was more clever than Gnasty anticipated and tracked down all the keys with a little perseverance.
Lock chests appear again in Spyro: A Hero's Tail, where Spyro had to require a Lock Pick in order to open locked chests.
Skylanders
In Skylanders: Spyro's Adventure, locked chests appear through the levels, sometimes behind elemental gates. The player known as the Portal Master in the game is the only one who open the locked chest by shaking the locks off in order to release the chest's contents, which contains gems, treasure, or accessories.
Gallery
A locked chest from Year of the Dragon
A locked chest as seen in Season of Ice" and "Season of Flame"