Consider the following:

Both Gen V and Gen VI minimised the amount of Surfing you had to do - you could get through BW without ever surfing, and in XY there was so little it didn't matter at all.

Alola is on 4 islands, and according to trailers 'there are many caves'.
>yfw there are huge undersea sprawling caves between the islands to explore
>yfw Game Freak put the comfiest possible underground area into Alola and they haven't even mentioned it yet