You have to pay to be a member of the Y, but the fees are reasonable, and the downtown branch offers swim lessons for all ages plus water aerobics classes at its indoor 25-meter, eight-lane pool. It's an easy walk or short drive from virtually everywhere downtown, so office workers panting to take a dip can fit it into their schedules. Better still, along with your swim you can work out at the Y's extensive aerobics and weight facilities upstairs, though do us a favor and hit the showers before jumping in. We once made the mistake of asking a lifeguard why the water sometimes tastes salty. You don't want to know the answer.