Aestival
"Sun! A great beam of sunlight bathes the island! Squint into the dazzle: far above, there's a hole in the roof. In that light you see beaches of white-gold sand; trees heavy with bright fruit; the reds and blues and greens of the Surface." [1]
Aestival is an island in the Unterzee, above which lies a hole in the roof of the Neath.
Oh, How I've Missed It
"No signs of violence. No fire, no bullets, no bites. These people died peacefully, sitting down to breakfast, as the Surface sunlight spilled over them. Sunlight can kill at any time. The longer you remain here, the more danger you're in. So why did they stay?"[2]
Surface sunlight streams through, bathing the island in its glow and triggering intense rushes of pleasure. It's beautiful, but deadly to denizens of the Neath, who die on contact with sunlight as the Sun reminds them of the laws of life and death. On the Surface, zailors will try to shield themselves from the burning sky, but many crewmen who arrive on Aestival will happily give themselves over to the sunlight, going out with one last smile.[3][4]
These factors, as might be expected, make Aestival one of the most dangerous places in the Neath. As a result, it is completely uninhabited, save for a few animals and dead bodies. It does make for a good place to harvest fruits and other bounties, but one must be careful.[5]
According to the Irrepressible Cannoneer, a meteorite-like Seal of the Red Science is what broke the roof of the Neath to let the sun in.[6]
