Genesis 8-11
Rain was apparently something that was new to the world with the flood. In Genesis 2:5-6 says that mist was the way that the ground was watered in the Garden of Eden and that rain hadn't fallen on the earth yet. So possibly the water cycle as we know it now didn't fully start till after the Flood.
Trying to build a model around what the Earth was like pre-Flood most creationists theorize that there was a layer of water around the Earth's atmosphere that prevented the sun's UV rays from being harmful. The water layer also would have helped to increase the atmospheric oxygen pressure and was what allowed for animals such as dinosaurs to grow so large. The same processes likely could have accounted for how everyone pre-Flood was living so long.
The longest living person in the bible was Methuselah who was 969 when he died as recorded in Genesis 5:27. Most of the causes to aging now is how quickly the protective ends of your chromosomes called telomeres degenerate. In a world with high atmospheric oxygen and close to no UV exposure that would have been fairly slow. People back then also would have had increased abilities to heal. Think of all the uses of hyperbaric oxygen now for helping to increase wound repair as well as fight infections. A pre-Flood person would likely have put the most health conscious people of today to shame when it comes to healing with how vital they likely were.
An interesting thought experiment would be to estimate all the water in the canyons of the ocean and estimate where the sea level would be if they were filled with rocks from all the highest mountains in the world today. Would it be enough to cover the entire globe? Enough to cover the tops of the then shorter mountains by 20 feet as Genesis 7:20 suggests?
There is certainly evidence that the oceans used to be much lower. Joe Rogan had a pod cast with Graham Hancock & Randall Carlson that go through some of the evidence for sever catastrophic world flooding.
Something else that is worth considering is that what would all that pressure from the water do to the covered vegetation. Would it be enough pressure to create the vast amounts of fossil fuels that are found around the globe?
Noah stepped off the ark into a new world. Archaeologists believe that they have found the remains of Noah's Ark by the Turkey and Iran boarder. See the YouTube video skip ahead to 2:30 of the video. It has low production quality but some very interesting ideas.
One thing that is fairly evident reading the genealogies from pre-Flood to post-Flood is that people were slower to have a recorded child and that the recorded ages rapidly decreased afterwards. Before the Flood it was 60-160 years before people were said to have a child and ages were routinely going over 900 years. Noah was apparently 600 when the flood occurred and only had 3 sons. After the flood people were starting to have families in their thirties and only living not far after 100 years once the story gets to Abraham.
Let me know your thoughts on these passages.