What's the Name of That Book??? discussion

Hi.
I am looking for an older kids or young adult fiction genre book, which i read at some point between 2006 and 2011. The book, I feel, was fairly new at that point- maybe a few years after it was published. I distinctly remember the new book smell.

It was a book series and i think the title or series name had something about smugglers or skeleton key or pirates maybe. In the book I'm remembering (which could even be the second or third or tenth book in the series) the main character and friend/s were spelunking somewhere looking for a key, or part of a map. I feel sure that they were looking for something specific. I think the main character was maybe 9-13 years old, may have had a twin sister or best friend/friends who he was exploring with. The story seems to have been well established in the book im thinking of, so it is very definitely possible that it's the second or third book. I think the covers were bright, with squiggly or bone-like font. Im definitely picturing a skull, and a key, and a map. Kids spelunking, sense of danger or urgency. It was wet, maybe someone fell or the rope broke. I do think that all of the kids got out alive and went in to a new adventure.

I dont remember much more as I was the type of kid to read 10-15 books in a week, and there are a lot of memories rumbling around up in my noggin.

I'll update if i remember more information.

I read this or a similar book but can't remember the title. Did the kids live in a B&B made from a converted lighthouse?

Missing on Superstitious Mountain by Elise Broach?

For the click:
Missing on Superstition Mountain

Chelsea, that sounds familiar, so it could have been a lighthouse.

Not "Missing On Superstitious Mountain" but that looks good so I'll check it out anyway.

Maybe the pyrates series? The first book is The Secret City, and its about a boy and his friends who find a piece of an old pirates map in his attic in manhattan, and they have to collect the other pieces in order to find the "key" or treasure. They find a series of tunnels under manhattan and are relying on spleunking equipment.

OMG, yes, I think that that's them. Thank you so much!!

Glad you found your series, Cassandra. Here's the link for the first book found by Eh - The Secret City (Pyrates #1) by Chris Archer.