The Navy had excellent charts with which to guide submarines through canyons and around guyots, but it didn't wish such information to fall into Soviet hands, so it kept its knowledge classified.
美国海军有着良好的海图,用来引导潜艇通过峡谷和绕过平顶海山,但它不希望这些资料落入苏联人之手,所以对它的信息加以保密。