Cave Survey drawing software

 Tunnel enables you to draw cave surveys based on Survex-compatible
 centreline data. Drawings will be adjusted to fit if the underlying
 data moves due to loop closures. Original drawings/scans/pockettopo
 imports can be used as a basis to draw over. Complex multi-layered
 surveys can be drawn, with flexible facilties for colour-grouping
 and adding images or background maps. The application can use data
 stored online and works on all major platforms.