Do I need to know how to swim to go scuba diving?

Yes and no. If you're participating in a trial dive or 'Discover Scuba' programme, you don't necessarily need to be able to swim since you'll be wearing a buoyancy control device (BCD) with which you can control whether you sink or float. However, if you're doing a certification course, some basic swimming ability is required. Your instructor will typically ask you to briefly demonstrate your swimming skills before you start diving.