22.when passing one fathom bank , check the depth and variable sand waves below the sea level all the time by echo sounder

通过一托浅滩时，要一直测深校时水深及海面下多变的沙绞。

Paul stepped out of the crack, watched the sand wave recede across the waste toward the new thumper summons.

保罗走出裂缝，看着沙浪越过荒地向新的重击召唤物退去。

A mound-in-motion ran parallel to their rock island—moonlit ripples, sand waves, a cresting burrow almost level with Paul's eyes at a distance of about a kilometer.

一个运动中的土丘与他们的岩石岛平行——月光下的涟漪、沙浪、一个几乎与保罗的眼睛齐平的顶部洞穴，距离大约一公里。