length of tourist visa stay?

Hey!

I read that you can stay 90 days within a calendar in SI. Is this correct? If not, can one extend there stay indefinitely?

Thanks,

Andrew

That is definitely correct, unless you have a residence permit, which needs to be applied for before you arrive, and renewed every 2 years.
It is possible to extend the 3 months once, if you go to immigration in Honiara with a good reason. (But be prepared to wait a while, in a queue, in the heat.)