To get there hop one of the many buses in the direction of Sariyer (such as the 20) and then at the last stop, catch the connector bus to Kylios, or you can find many dolmuºes around to take you to Kilyos. The buses will drop you off right on the edge of town, and then from there it is only a 5 minute walk to the main beach. Access to the beach will cost you 5 million TL. Many hotels have private fenced in areas too, that you can get access to for a fee.

In terms of watersports Kilyos doesn't have much to offer. The Black Sea isn't one of the most beautiful in the world, but it is pleasant nonetheless. Kilyos is easily done as a day trip, although best not to go on weekends; it will be too crowded, but you can also stay a night. The town of Kilyos is a pleasant village with plenty of restaurants, and at night there are a few good nightclubs that often attract some of the best DJs in the world (Sasha just played there in August). So if you want to escape Istanbul for a day and take a pleasant dip in some cool water, head to Kilyos and you won't be disappointed.

One word of caution though: The Black Sea has a notoriously bad undertoe, so be careful, the swimming areas are roped off for a reason!