Very cool concept, though I feel like it might be challenging to run as I personally found some of the descriptions difficult to parse what exactly was happening (could very well be a me-problem). The overall imagery/design matches the themes of gravity and sinking perfectly IMO.
The writing was succinct and evocative but I think could use a bit more clarity; the room descriptions could’ve also been more consistent with bolding for ease of reference (e.g. sometimes interactive encounters/elements were bolded, sometimes not.)
The general layout might have slightly better usability at the table if the map was adjacent to the keyed descriptions and was preceded by the Encounters page, not separated by it. Likewise, the page with Burdens/Signs/Environment/Treasures (which is an excellent section BTW for verisimilitude) I think could’ve been left near the end. (Again just personal preference; I’m certainly no layout expert.)
Finally, I think the last page should have been put to use further develop the adventure instead of leaving it pretty much blank; I do see how it visually bookends the leaflet, but one could’ve still made use of some of the space.
That all said, an excellent entry!