Something that's landlocked is completely surrounded by land, rather than by bodies of water. Oklahoma City is landlocked, but San Francisco isn't.
There are many landlocked cities in the world, and if you live in one of them but miss the time you once spent on an island in Maine, you may feel landlocked yourself. There are only 42 truly landlocked countries in the world, whose borders don't touch open ocean. Historically, most of these landlocked countries have struggled economically, since access to ocean shipping makes it easier to export goods.