So lets make this a general, hypothethical discussion.

Why would I be concerned about?

Your want to be careful about the water, wash frequently and keep any wouds covered. Sunscreen!

Communication is an issue, as is getting power. I'd learn & carry a 2 m ham radio, also my cell and expect it not to work.
Batteries!

Bring a gps and a map, in case you lose your group and need to walk out. ( also a bunch of plastic sheetig to catch rain water)

Life jacket and mabye a ballistic vest, Baby wipes!

MRE's? Either check with friends or raid your family supply and mail order some new ones today to replace.

TRO