Can we access this cave in Poni Meadow?

As of right now, it appears that this cave is inaccessible. This is one of a few places that just beg to be explored but have no way to access. A partial list of such places was compiled here:

• water pools/springs area in the second island isn't accessible (http://www.gamefaqs.com/boards/187276-pokemon-sun/74566119).
• the golf course in the second island isn't accessible.
• you can't explore the volcano on the second island. instead you just teleport between entrances and exits
• the huge mountain in island 3 also isn't explorable, apparently there's a random bus stop that takes you to the top and presumably back down
• something like 75% of buildings in the game aren't accessible, including the lighthouse on the second island.
• and of course, the empty plots of land we already know about

While the cave you (and I) want to enter isn't listed, other users have been searching for an entrance (to no avail), like here:

There is a cave on the water at the Poni Meadow but because the water is apparently 1 foot below you, you can't use your water ride pokemon. There seems to be a stream leading from the pond outwards to somewhere, which I assume meant there was an entrance somewhere to the other side of the stream but I for the life of me can NOT find it. >_>

Another place that seems to confirm its non-entry is Serebii's Pokéarth page for Poni Meadow, as the only listed exits are to Poni Plains and Resolution Cave (which only has one entrance and it is above this cave).