Interest Check: Project Monarch
I expect most of the story to deal with... shall we say extraordinary. Think King Kong (2004) movie. Kong (or other MUTOs/Kaiju) are basically boss monsters, but to get to them you'll need to get through... oh say... roaches the size of a dog, weird locals, thought to be extinct species, giant leech things, magnetic and other navigational anomalies, freak weather, and so on.
However, there will be nothing supernatural in essence... but there might supernatural in appearance. For example a local shaman might be able to read your thoughts, but that's cause he is a telepath, not cause he is a wizard. "Science is magic" basically. :D