If I was to add sea routes to BT I'd add two:
- Iato-Ofengail (Ofengail because it was next to a city and would be a likely place for a port on the west coast)
- Fronepu-Melegra (Melegra because the old bridge to Fwuvoghor could be the new 'port' for boats to land at)
Other Possibilities:
Gethsemene-Sandefur-Agyr (A northern sea route opened by the loss of some of the northern regions)
Fronepu-Rines-Grehk
Heen-Iato-Ete City
Athol Margos-Mhed
