A waterside leisure facility comprising: an enclosure (100; 200; 300; 400; 500; 600), covering and surrounding: an area of land mass (101; 201; 301; 401; 501; 601) sized to accommodate a group of users of the facility; an enclosed portion (103; 203; 303; 403; 503; 603) of a body of water (102; 202; 302; 402; 502; 602), the enclosed portion (103; 203; 303; 403; 503; 603) sized to accommodate a group of users of the facility; the land mass (101; 201; 301; 401; 501; 601) having a shore front adjoined to the portion of the body of water; the enclosure (100; 200; 300; 400; 500; 600) further comprising: a dividing wall (104; 204; 304; 404; 504; 604) separating the enclosed portion (103; 203; 303; 403; 503; 603) of water from the remaining portion of a body of water (102; 202; 302; 402; 502; 602); a transparent roof (106; 206; 306; 406; 506; 606), joined to the dividing wall (104; 204; 304; 404; 504; 604) and surrounding the area of land mass (101; 201; 301; 401; 501; 601), to substantially separate air in the enclosure from ambient air outside the enclosure (100; 200; 300; 400; 500; 600), while letting light through the roof (106; 206; 306; 406; 506; 606); water treatment means arranged to maintain the water in the enclosure (100; 200; 300; 400; 500; 600) at a controlled temperature; and air conditioning means arranged to maintain the ambient air inside the enclosure at a controlled temperature and humidity. an enclosure (100; 200; 300; 400; 500; 600), covering and surrounding: an area of land mass (101; 201; 301; 401; 501; 601) sized to accommodate a group of users of the facility; an enclosed portion (103; 203; 303; 403; 503; 603) of a body of water (102; 202; 302; 402; 502; 602), the enclosed portion (103; 203; 303; 403; 503; 603) sized to accommodate a group of users of the facility; the land mass (101; 201; 301; 401; 501; 601) having a shore front adjoined to the portion of the body of water; an area of land mass (101; 201; 301; 401; 501; 601) sized to accommodate a group of users of the facility; an enclosed portion (103; 203; 303; 403; 503; 603) of a body of water (102; 202; 302; 402; 502; 602), the enclosed portion (103; 203; 303; 403; 503; 603) sized to accommodate a group of users of the facility; the land mass (101; 201; 301; 401; 501; 601) having a shore front adjoined to the portion of the body of water; the enclosure (100; 200; 300; 400; 500; 600) further comprising: a dividing wall (104; 204; 304; 404; 504; 604) separating the enclosed portion (103; 203; 303; 403; 503; 603) of water from the remaining portion of a body of water (102; 202; 302; 402; 502; 602); a transparent roof (106; 206; 306; 406; 506; 606), joined to the dividing wall (104; 204; 304; 404; 504; 604) and surrounding the area of land mass (101; 201; 301; 401; 501; 601), to substantially separate air in the enclosure from ambient air outside the enclosure (100; 200; 300; 400; 500; 600), while letting light through the roof (106; 206; 306; 406; 506; 606); water treatment means arranged to maintain the water in the enclosure (100; 200; 300; 400; 500; 600) at a controlled temperature; and air conditioning means arranged to maintain the ambient air inside the enclosure at a controlled temperature and humidity. a dividing wall (104; 204; 304; 404; 504; 604) separating the enclosed portion (103; 203; 303; 403; 503; 603) of water from the remaining portion of a body of water (102; 202; 302; 402; 502; 602); a transparent roof (106; 206; 306; 406; 506; 606), joined to the dividing wall (104; 204; 304; 404; 504; 604) and surrounding the area of land mass (101; 201; 301; 401; 501; 601), to substantially separate air in the enclosure from ambient air outside the enclosure (100; 200; 300; 400; 500; 600), while letting light through the roof (106; 206; 306; 406; 506; 606); water treatment means arranged to maintain the water in the enclosure (100; 200; 300; 400; 500; 600) at a controlled temperature; and air conditioning means arranged to maintain the ambient air inside the enclosure at a controlled temperature and humidity.