A Sandbar?

After having the closer look the crew assumed it to be a sandbar floating amidst the ocean. Of course, it is not something unusual as the sea is full of major and minor sandbars floating around. But the sandbar they came across was anything but usual. The crew thought they have finally resolved the mystery but the truth was they were still miles away from the truth. However, as the fate had it, the demystification of the mystery behind this gigantic sandbar was going to be resolved by them only.