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

I read this book around 2010 in middle school. It was definitely written pre 2000s. It followed the story of a group of marine biologists on a submarine excursion into the deep dark depths of the ocean. I think there was a giant creature or alien swimming around that slowly began infiltrating the submarine and killing the crew members one by one. My memory is very hazy so I can’t remember if all this is accurate, I think the cover had a circle on it and was blue and for some reason I keep on thinking the title was either one word or contained a number in it, I’m not sure. If anyone has any idea of what I’m talking about please let me know!

Devayani, is this book for teens or adults?

Who do the scientists work for? Which country(s) are they from?

Sphere?

Jon wrote: "Sphere?

"

Yes that’s it!! Thank you so much!!!