The fourth channel that traditional channels pass through is

Analysis of test questions: judging from the latitude and longitude position and land and sea distribution, ① it is the Strait of Gibraltar; ② English Channel; ③ Straits of Malacca; ④ It is the Mande Strait, so the shortest route from China to Germany goes from east to west through ③ ④ ① ②.

Comments: The key to solve this problem is to judge the distribution of world-famous straits by using latitude and longitude positions and sea-land contours. This problem can also be designed in combination with the direction along which the ocean current passes.