I've been working on GeoTraceroute for a while and just shipped v2.3 with submarine cable inference.

A few things that might interest HN:

- 320 community-contributed nodes across 50 countries, all volunteer-run - Three views: 3D globe with day/night rendering, 2D map, and a topological mode that infers submarine cable routing - The submarine cable inference is the part I find most interesting. Since cable routers don't respond to ICMP, the underwater segments are invisible to standard traceroute. The tool detects ocean crossings by geolocation delta between consecutive hops, then infers the likely cable using a geo graph of landing points with A* pathfinding. I have no way to validate this — if anyone has ideas, I'd love to discuss.

Coverage is good in EU and US but thin in Asia, Africa and South America. If you want to contribute a node: https://geotraceroute.com/join

Salim