Nature:

Enter Raindrop, a phone application that combines sewer and watercourse maps with the software that makes getting a caffeine fix so easy. Tap the map and watch the path of a single raindrop flow from your location through streams, culverts and pipes into the river. The app, due to launch next month, was funded by the US National Oceanic and Atmospheric Administration and put together by a team led by ecologist Timothy Carter at Butler. It is currently limited to Indianapolis, but similar efforts could be designed for other cities.

A better appreciation of watercourses and other hidden networks can only strengthen human connections to ecosystems, biogeochemical cycles and resource flows, and will arguably make people more likely to support science and environmental causes.

I wish it could also follow a raindrop through a single human body—in and out and down the drain. Our science writer, Golob, once called a city a massive river. There is also a theory out there that calls life on land a hypersea.