He didn't want her watching him as he jumped off. So long as no one was watching he would be able to say afterwards that he had slipped and fallen by accident. He peered over the side of the ship. It was a long, long drop.
Source: Roald Dahl: Dip in the Pool
I do not fully understand the last sentence of my excerpt. None of the meanings of the word "drop" make sense to me here. Given the context (the man is preparing to jump off the ship) the only explanation is that the sentence describes the protagonist's assessment regarding the height from the side of the ship to the surface of the sea. Am I right?