Monoculars follow a lot of the same rules as binoculars since they are, in fact, one half of a pair. They make a great hyper-portable selection and most will fit easily in a pocket. They are best used for quickly spotting things rather than long observations. Waterproof models are particularly perfect for boating, where you need one hand free to hang on to the boat. Monoculars also make a great partner to a high power spotting scope to serve as a comfortable hand-held finder.