Jam Island is one of 34 islands surrounding Whole Cake Island as part of the Big Mom Pirates' main territory known as Totto Land. It is run by a minister like other islands on Totto Land.[2] It is the second island of the Charlotte Family siblings' secret route to Whole Cake Island.
Jam Island has buildings model after glass mason jars, commonly used to store food such as jam.
References
↑ 1.01.1One Piece Manga and Anime — Vol. 83Chapter 829 (p. 3-4) and Episode 788, The Sanji retrieval team spot Jam Island before continuing their journey.