User blog comment:Mythical zoan fruit enthusiast/For those who want Luffy to have Mera Mera and Gomu Gomu/@comment-195.241.127.96-20130503222528/@comment-195.241.127.96-20130504212855

correction, he did put half his hand in the ocean and did Ice Age. but it's probably like luffy did in fishman island with a part of his body only in the water. So unless they are not for a big part in water they are still able too use ability.