Well that narrows it down. Let me see...alright, here are the maps and their locations:
#2, dig spot inside Wafayer Hideout #2
#4, speak with Kayo (after he's buried) and go to where he points out
#9, purchase off man who shouts a lot at Mercay Harbor (tell you have the cannon)
#11, shoot eye crest on Ocean King Temple B6
#23, in Ocean King Temple, use bombs/bombchu to access B4 NW stairs, NW chest in B5 (blocked by gust jar)
Btw, the last two on Harrow Island you can get after you get the last Sea Chart.