YA: friends go on holiday, end up in a basement (I think), discovering secrets. Read about 10 years ago

[[deleted user]]

I think the title has ‘summer’ in it. The cover of the book i remember reading was mostly water with a girl in a red swimsuit floating on the water.

[Merannda]

What age range would you put the friends in? Do you recall where the holiday trip was too? Like a beach, mountains, city, etc?

[[deleted user]]

I think the friends were probably teenagers. I can recall there being a house with a pool, not too sure where though