1. We play tennis, go sailing, swimming and skin-diving.

2. Scuba diving" is basically skin diving with scuba gear, usually an "Aqua-Lung" that lets users breathe under water.

3. ‘The Resort includes lakeside Boatels with lofts, cozy cabins, and luxurious rooms - some with Jacuzzis - within the facility's modern hotel complex.’ ‘There were Boatels too that provided services like docking and renting of boats for boating, water-skiing and skin-diving lessons.’

4. In what follows, I summarize the economic potential for the world's major cities for "rubber and rubberized dry and wet suits, scuba, skin diving, Aqualungs and attachments, face masks, fins, and other underwater sports equipment excluding cameras and watches" for the year 2013.