I am intrigued by the notion of this efficient method of shipping to coastal regions. There have been many studies on urbanization that have highlighted how many people live near oceans. Currently the UN estimates that 40% of the world population lives within 100 km of a coast: http://www.un.org/esa/sustdev/natlinfo/indicators/methodology_sheets/oceans_seas_coasts/pop_coastal_areas.pdf
Most analysts predict that populations will continue to concentrate towards dense coastal cities.
One thing that people don't often think about when it comes to teaching is that it requires managing a group of people. One hidden benefit of your idea is that it trains young kids to become leaders. It takes guts to stand up in front of your peers, and it also requires public speaking skills. There is no better way to improve your public speaking ability than by simply doing it.
Geronimo, this idea is fantastic. I think the most exciting thing about this idea as a donor is how the gift keeps on giving, and potentially multiplies!
One thing I am a little bit concerned about is giving the donor too much power in managing their donation when there is a whole heap of work to be done on the loan servicing side. For example, microfinance organizations in India create branches that extend way out into every community they service. To reduce the burden of debt collecting, some microfinancers implement programs where a group of 5 borrowers might be pooled together in their responsibility to pay back the loan. The social pressure created by this program reduces the default rate and reduces the labor for the microfinance organization.
My point is that coordinating the donor's preferences with the microfinancier's operations would likely be a challenge for some regions. Rather than selecting specific requests for loans, it might be more efficient to select categories such as "empowering women in India."