The woman who does this is named Leo, and she has her own stable of 7 horses. "Trikk Pony Adventures" http://trikkpony.com/
The only trail rides she does are the beach rides. She also gives lessons at her barn. (she used to do show jumping in France). She picks you up at your hotel with horses in trailer in tow, and drives you straight to the beach. The entire ride is on the beach. Highly recommended. The horses were well cared for, and my girlfriend who is nearly 6' tall rode a 17 hand draft cross. I got to ride a very well mannered 4 yr old Doc O Lena bred baby My other friend who has NO riding experience at all, rode a wonderful QH mare. The mare really took good care of her. Riding in shorts is a necessity because you're in the water up to your ....umm....water covers the saddle I never realized how slippery synthetic saddles get when they're wet! All in all, it was a fantastic experience. check one more off the bucket list.