IPA: /ˌɪntəˈraɪlənd/
KK: /ˈɪntərˌaɪlənd/
Relating to or connecting two or more islands.
The interisland ferry service makes travel between the islands easy.
Interisland → It is formed from "inter-" (meaning between) and "island" (from Old English "island", meaning land surrounded by water). The word "interisland" refers to something that exists or occurs between islands.
Think of things that happen 'between' ('inter-') different 'islands' — that's what interisland means.