How long is one yojana?

In the Satta Surya Sutta, it says: “The ocean will sink by one hundred yojanas, two hundred, three hundred, four hundred, five hundred, six hundred, even seven hundred yojanas.” However, the ocean’s maximum depth is only about 11 km. One Yojana is generally considered to be around 10–15 km, so 100 yojanas would be about 1,000–1,500 km. Does this mean that the yojana used at that time was shorter than this?