With the recent first detections of gravitational waves by LIGO and Virgo, it is both timely and appropriate to begin seriously planning for a network of future gravitational-wave observatories, capable of extending the reach of detections well beyond that currently achievable with second generation instruments.

The GWIC Subcommittee on Third Generation Ground-based Detectors is tasked with examining the path to a future network of observatories/facilities, specifically:

1. Science Drivers for 3G detectors: commission a study of ground-based gravitational wave science from the global scientific community, investigating potential science vs architecture vs. network configuration vs. cost trade-offs, recognizing and taking into account existing studies for 3G projects (such as ET) as well as science overlap with the larger gravitational-wave spectrum.
2. Coordination of the Ground-based GW Community: develop and facilitate coordination mechanisms among the current and future planned and anticipated ground-based GW projects, including identification of common technologies and R&D activities as well as comparison of the specific technical approaches to 3G detectors. Possible support for coordination of 2G observing and 3G construction schedules.
3. Networking among Ground-based GW Community: organize and facilitate links between planned global 3G projects and other relevant scientific communities, including organizing:
   
   • town hall meetings to survey the community
   • dedicated sessions in scientific conferences dedicated to GW physics and astronomy
   • focused topical workshops within the relevant communities
4. Agency interfacing and advocacy: identify and establish a communication channel with funding agencies who currently or may in the future support ground-based GW detectors; communicate as needed to those agencies officially through GWIC on the scientific needs, desires, and constraints from the communities and 3G projects (collected via 1) -- 3) above) structured in a coherent framework; serve as an advocacy group for the communities and 3G projects with the funding agencies.
5. Investigate governance schemes: by applying knowledge of the diverse structures of the global GW community, propose a sustainable governance model for the management of detector construction and joint working, to support planning of 3rd generation observatories.