|View of Macau, China, from Zhuhai, China (February 2015)|
You could try swimming from the location in Zhuhai where I took the above photo to Macau. I stress "try". Even if you reached Macau, the relevant authorities would likely prevent you from getting much farther, and what follows would likely not be a pleasant experience. Reaching Macau would be far easier if you simply walk to the nearby immigration and control point and cross the border on land, assuming you have the relevant documents. Many Chinese people I have met in the same area did not though. But if you do make it to Macau from Zhuhai, regardless of the method you use I wouldn't call it "overseas travel".