The Lakes of Killarney are Lough Leane (the lower lake), Muckross Lake (the middle lake), and the Upper Lake. These lakes are interlinked and together make up almost a quarter of the park's area. Despite being interlinked, each lake has a unique ecosystem. The lakes join at the Meeting of the Waters, a popular tourist area. Sport angling on the lakes has been a pastime in the area for some time, in particular of the lakes' brown trout and salmon populations.

Lough Leane is approximately 19 square kilometres (4,700 acres) in size and is by far the largest of the three lakes. It is also the largest body of fresh water in the region. It is also the lake richest in nutrients. It has become eutrophic as a result of phosphates from agricultural and domestic pollution entering Lough Leane Reedbed, an important habitat on the edge of Lough Leane. This nutrient enrichment has caused several algal blooms in recent years. The blooms have not yet had a severe effect on the lake's ecosystem. To prevent further pollution causing a permanent change in the lake's ecosystem, a review of land use in the catchment area is being carried out. Water quality in the lake appears to have improved since phosphates were removed from sewage in 1985. As of August 2007, several large hotels and businesses have stated their intention to stop using phosphate detergents, in an effort to preserve the quality of the lake water.

Muckross Lake is the deepest of the three lakes. It has a maximum depth of 73.5 metres (241 ft), close to where the steeply sloping side of Torc Mountain enters the lake. The lake lies on the geological boundary between the sandstone mountains to the south and west and the limestone to the north.

Lough Leane and Muckross Lake lie across the geological boundary. The presence of limestone causes both of the lakes to be slightly richer in nutrients than the Upper Lake. There are many caves in the limestone at lake level, created by wave action combined with the dissolution effect of the lakes' acidic water on the exposed rock. These caves are largest on the northern shore of Muckross Lake.

From the Meeting of the Waters a narrow channel called the Long Range leads to the Upper Lake, the smallest of the three lakes. This lake is located in rugged mountain scenery in the upper Killarney/Black Valley area. The fast run-off in its catchment area can cause the level of the lake to rise by up to a meter in a few hours during heavy rain.

Muckross Lake and the Upper Lake are high quality oligotrophic systems, with water that is slightly acidic and low in nutrients. This is caused by run-off from the upland sandstones and blanket bogs in their catchment areas. They have diverse aquatic vegetation, including quillwort (Isoetes lacustris), shoreweed (Littorella uniflora), and water lobelia (Lobelia dortmanna).

All three lakes are very acid sensitive and therefore vulnerable to afforestation within their catchment areas.
https://en.wikipedia.org/wiki/Killarney_National_Park

This is a beautiful section of the Killarney National Park. The weather was threatening with rain on and off so we didn't get to see any blue water but the storm clouds added their own charm. All of these were taken through the tour bus windows with a Nikon D7500 and 18-300 lens at 1/640 sec f5.6 auto iso. I hope you enjoy them!
Mark