If you live in a city that has an Indonesian Consulate (like Los Angeles) it should be easy to get to a sixty day visa.
Consulate General of Republic of Indonesia - Los Angeles - Consular/Immigration is the LA Consulate's web site
From that site:
Visitor's Visa (for
Tourists, Business, Social-Cultural, Journalist, Research) - Extendable : Visitor’s Visas are given to Regular Passport holders and issued to applicant who visits Indonesia with the purpose of directly related to Tourism, Business, Social-Cultural, Journalist and Research for up to 60 days. (Single/Multiple) Visitors Visa US$ 45.00 Can take three business days if you drop it off and pick it up in person Located on Wilshire Blvd, just west of downtown Los Angeles.
Requirements
Valid Passport (at least 6 months beyond entry date/passport expiration date)
Two recent color passport size photograph
Copy of Itinerary/Return or onward ticket
For non-US Citizens : copy of valid Green Card (please show the original)/ Valid US Working Visa/Employment Authorization
Guarantee Letter from sponsor or employer describing the purpose of the visit and guaranting all transportation and living expenses that willincur in Indonesia / copy of Supporting Letter
(
you would have to ask exactly what they want, maybe a letter from the Dive Resort saying that you have booked for a certain time period)
Two Visa Application Form (can be found at the bottom of the actual web page)
Receipt payment from Cashier