It has a lot of capacity to choose, 10L/20L/30L liters of these three are more common, you can be measured in accordance with the 5 ~ 10L / person's needs, for example, 3 people travel, then 5 * 3 = 15L above the package is feasible .
The price of an ordinary waterproof bag is about RMB 100 to RMB 150. The price of a professional or international big waterproof bag can reach 700 to 1,000 RMB. Personal advice, buy a waterproof backpack about a hundred dollars is good, and next time you go to mountaineering, sports, swimming, gym can be used in many occasions.
As for the mobile phone waterproof bag, everyone should be familiar with it. However, you may not have any luxury in the photographs of mobile phones with waterproof bags. Professional underwater photography equipment is your best choice.