The land ecosystem, in spite of its relative youth, outstrips the marine ecosystem in terms of greater primary productivity and species diversity per unit area. This occurs because land eukaryotes actively direct the flow of nutrient-rich fluids. The body fluids of land eukaryotes have had a significant evolutionary and geochemical impact, and we here refer to these fluids, and the organisms through which they flow, as 'Hypersea'. Hypersea is a previously unrecognized biogeophysical entity formed by eukaryotic life and its symbionts, parasites and hyperparasites on land. The oldest convincing evidence for Hypersea consists of fossil tracheophytes, mycorrhizal fungi, and protoctists displaying intimate ecological interactions in the Lower Devonian Rhynie Chert (approx. 400 million years old), just older than the first major coal deposits. We use the concept of hypermarine upwelling to help explain both (a) the genesis of coal and (b) why the average species diversity per unit area and biomass production of the land biota has exceeded that of the marine biota for hundreds of millions of years.