If this is a tropical island with a lot of flora and fauna I'm pretty sure I could improvise or find new and amazing stuff to cleanse and condition my hair. But gots to have my henna - I 'm not sure if there's a substitute for that.
I would take
1. herbal infused olive oil (with aurvedic powders and tea tree oil)
2 Lifetime supply of henna and indigo (mixed powder) in a double plastic bag!
3. My aloe- vera glycerine mix
Now you know I would be wearing my large thick satin silky head rag to the island!!!!!