On the Ten Thousand Nations Continent side, the entrance to the Starship's interior was originally supposed to be a door.
The door had been dismantled, leaving behind an oval opening about 3 meters along the long axis and 2 meters along the short axis. Beyond this, there was another equally sized door that closed vertically, but it too had been violently destroyed. Passing through that door and walking forward for a dozen meters or so before turning left, you would reach the wide, straight main passage.
The Dulai Flame Spiders are naturally large creatures. An 8th Age-Period mid-level warrior could span nearly 1.3 meters in leg span.
In the field test, the Little Flame Spider named Natsumi could easily pass through.
It's estimated that up to a 7th Age-Period high-level warrior could squeeze through.
For the next ten years or so, Natsumi would be responsible for transporting trade goods between Dragon Cypress and Seven-Leaf.