YA Fantasy about protagonist trying to bring their friend/ sibling back from the dead. Read around 2017-2019.

[Stephanie]

Unfortunately I don't remember much details about the story itself. I happened to be reading it while a family member got very sick in hospital and died. I thought in hindsight the fact the story focused so heavily on death was rather ironic, given the circumstances.

I'm pretty sure it was a YA book and I bought it in ASDA (British Walmart) sometime in or before 2019 (likely 2017-2019). In the place the story was set when people died they were placed on a raft of some sort and pushed out into a body of water. The body then went down into a large hole. The main character's friend or sibling (I can't remember which) dies and they decide to follow them down into the hole to attempt to bring them back from the dead.

The title may have had a word like abyss or precipice in the title but I'm not 100% sure.

[Rainbowheart]

Was the main character male or female?

How about the friend/sibling?