Two groups studied a list of words either on land or underwater. The land group was able to recall more words on land than underwater, whereas the underwater group was able to recall more words underwater than on land. What does this example represent?

It refers to context cues or context-dependent memory. In psychology, the retrieval of items can be more possible and easier when the context or setting of recall is the same as the context in which the item is learned. For example a rainy day, a particular house, a certain place can be context cues or retrieval cues.