Can You Turn Existing Inground Pool Into A Shallow Pool With Spa?

[WooBah]

Hi, I have an inground gunite pool, kidney shaped, 3 feet to 7 feet depth, dimensions are approximately 23 x 38. There is also a rock water fall. I had the pool built when my house was built. I had NO clue about pools when I first built it. The pool is very nice, but I find that the deep end is rarely used, and it takes awhile for the water to get warm. I live in Central California where temps are uppper 90's to low 100's in the summer, and the swim season is a good six months. I also wish I would have got a spa with the pool, I realize I can still buy a portable above ground spa, and those so seem to be popular. But, if possible, and if possible financially, I would prefer a built in spa, which I believe would be a better overall look.

Is is possible to turn this existing pool into a shallow pool, say 3 to 4 feet depth for the entire pool, with a built in spa, which would seat 6 to 8 Adults in comfort, all in the space of the existing pool? Or, is this not practical? Or, are the costs not worth it?

Thanks for any input.