This is how Arkanemancer described them:
"These 'Sea Gnomes' aren't like any other gnomes I've ever seen before. For I do not think that they are actually related to the regular gnomes of Gnomeregan. They swim like fish and have a dialect similar to those of the murlocs. It is amazing how they are here and have been kept a secret for so long, because of there giant mechanical wonders they have made."