On our core worlds, we have one mountain range and that's it. In the sectors, neither are particularly common but there are seven mountain ranges, and only one quicksand basin(which occur only on the drier planet types that we can't colonize yet, apparently). So
Mountain Range Removal it is.
This is the most relevant section of our most recent star chart. We have explored a significant amount of territory 'below' the Djomar as shown, and there at least two large, habitable planets in that area. No sign of any other empires in that direction so far. Both the remains of the Kroll and the Djomar are by this point insignificant compared to use militarily. It would be an easy war, the question is whether or not it is worth the effort. We could still expand in the other direction towards the fallen empire. We don't need the war to expand here either, but if we don't clear a path we would be in a situation where part of the Collective could be 'cut off' -- if one of the empires in the way decided to close their borders, we would be unable to get through. The other way to maintain continuity would be to attack the small Scyldari Conferderacy along the 'Qravadox Corridor'. Taking Obnoll, their small ocean planet here, would give us access at least for now along the outer arm.
There are no significant relations with other empires to consider in either case. It would probably take two more wars to knock out the Kroll and Djomar completely. Djomar worlds(tropical preference) are not as suited to us as the ocean-favoring Kroll, but in addition to their slaves, there are two large arctic and a smallish ocean world that have been unsettled within their territory based on our continued survey efforts.
The truce is up in the middle of 2060, next year. At that time, what should we do?
**
War with the Bright Compact -- Attack the Kroll/Djomar again. We could just take the remaining Kroll system, or push into Djomar space as well. It would probably take two more wars to knock them both out completely, due to limitations of war demands. Just taking out the Kroll would mean only one. Couple of choices here.
**
War with the Scyldari Confederacy -- They have just three systems, so we could knock them out easily. They have no relations at all with the Qravadox, so we wouldn't be risking a fairly strong enemy by doing this, but we would be sandwiching Qravadox space with a couple of worlds via this route and it could lead to rising tensions over time. The Qravadox Corridor would be opened to us, perhaps or perhaps not permanently(there are other systems that I don't think either empire can settle yet that would need to be claimed to make it permanent).
**
Keep the Peace -- Focus on expanding peacefully where we can, without the disruption of war throwing a wrench into things. As we found after the Kroll invasion, newly conquered territories can be disruptive for a time, and maintaining a large fleet away from port would definitely put pressure on the rest of the economy. If we choose this route, we'll also need to decide whether to colonize the 'disconnected' territories past the Djomar, or focus only on those we can guarantee access to.
Inquisitor Roe Laren has the final word here, and is on the clock. What say the leadership of the Collective?