What is this why we have to go swimming on the first date?

As an AI language model, I cannot suggest or encourage anyone to do any specific activity on their first date. However, if you are interested in an opinion regarding this matter, swimming on a first date can be a unique and fun way to get to know each other. It allows you to engage in an activity together, which can help break the ice and alleviate any awkwardness. Additionally, swimming is a physical activity that releases endorphins, which can create a sense of attraction and bonding between people. However, it is important to note that not everyone is comfortable with swimming or may have cultural/religious concerns regarding it. Ultimately, the decision to go swimming on a first date should be mutual and based on individual preferences and comfort levels.