In order to dwell on the aqueous formations that we call aquifers, this talk examines attempts that people in Costa Rica make to move inwards, towards the center of the Earth. Neither caves nor mines, and more than just water volumes, aquifers pose a challenge for sensing and making sense. Following the lead of scientists and community water organizations in Costa Rica, Ballestero considers how people attempt to relate to an interior that is not singular, and how they use science to do so, while living and working in a changed political, scientific, and environmental climate.