“下潜”的英语？

“下潜”的拼音为：xià qián...

潜水员下潜到超过危险线的深水中去了.The diver went into the deep water beyond the danger limit.为了下潜,里边还有个密封小水槽―负槽.For diving there's small sealed tank inside, the negative tank.潜水艇的下潜速度非常快.Submarine can submerge very quickly....