The Sea, An Island, Vacation! The Soldiers' Relaxation
The Ocean! The Island! A Vacation! A Break for the Sailor Warriors
Umi yo Shima yo Bakansu yo! Senshi no kyusoku
"The girls enjoy some vacation time on an island. But during lunch Chibi-Usa and Rei get into a small fight, causing an angry Chibi-Usa to go out to the sea alone." (source)