He is actually offering comfort and reassurance to the eight people who will endure the world's horrible destruction. This is clearly established once Noach completes Ha Tay Vaw. In realizing this we observe Hashem's care for the residents of the ark as mentioned in the twenty-two occurrences of Ha Tay Vaw. Again, there is no way to describe what the eight survivors experienced but it does help to know that Hashem prepared the survivors, guided them and assisted them in reestablishing after the flood. House implies a building, a structure, a place of gathering, a place of living, a place of learning and more.
Oceans are now mountains.
Seas are plains. Mountains are oceans. The water canopy covering earth has been removed. The hemisphere has changed. Temperatures are no longer constantly hovering around 72 degrees.