Sea horse mount and a giant lizard mount
and sea dragon mount

with the sea horse mount there can be a map ONLY for the sea horse that is under water and you fight under water creatures like sharks and such "custom sea animals and stuff" limited to only people who buy the sea horse and or sea dragon mount

the lizard mount can be for like 4-8 thousand balens and can run 3%faster while on sand "habitat benefit"
and can be upgraded to 5% faster on sand