Marine research and monitoring costs are extremely high, which helps explain why we know much less about what goes on in the ocean than about what happens on land. The same also applies, to a certain extent, to human activities. This renders two-dimensional maps less useful, and increases the complexity of marine spatial planning and management. It also makes it more difficult to study the marine environment, how it works, how it is affected by human activities (see difference #2), and how the ocean benefits the economy and human well-being. What makes the ocean economy different from a land-based economy?