Terragen 4.4.44, Pixelmator Pro 1.7
Reference photo here: http://www.runladylike.com/wp-content/uploads/2016/07/IMG_2247-1024x768.jpg
Also available @ https://www.deviantart.com/jhmartinez/art/Crater-Lake-852045399
Crater Lake reference photo.
http://www.runladylike.com/wp-content/uploads/2016/07/IMG_2247-1024x768.jpg