My sister and her friends...

[Palakaboy]

all dancers, at the beach.

 

[Early]

Hey, not bad! Four girls, four different looks. Good composition, btw. The only thing that turns me off is all the litter.

 

[GotaLuvThosPens]

love the poses and the blue but I really wish the lighting was on the legs and feet as well. You also need to straighten out the horizon just a tad.

 

[Derrel]

Hey, cool! Lovely ladies, and a nice photographic treatment.

 

[AlexL]

nice color and I love the way the light brightens up the face! Good Job!

 

[Laika]

This is an excellent shot. I agree that the horizon is slightly tilted, but it isn't enough to bother me or make me think less of the image.

 

[Rosshole]

what lighting was used for the shot?

 

[Derrel]

This scene has the look of a photo made with the camera deliberately set to Tungsten white balance, and an orange-ish CTO gel placed over an electronic flash---that orange light will be rendered as white light, due to the off-kilter white balance, and the natural light from the sky will go excessively blue. Using that method, it's possible to turn an ugly gray sky into a blue sky. I am guessing that this photo was made in a similar fashion; perhaps the OP will enlighten us?