Imagine if the oceans were replaced by forests just as vast, and the further you went through them, the taller the trees became and the darker your surroundings. The small fish would be replaced by new insects and colourful bugs, and as you got deeper into the forest, the animals would get progressively scarier so the whales would be replaced by giant, majestic deer and the sharks would become fiery foxes, double their normal size. There would be a plethora of undiscovered plants and animals in the same way as there are in the oceans; but they would be more accessible since the probability of survival would simply depend on the bravery of the explorers and scientists rather than the nature and efficiency of the surroundings compared to human limitations.