An exchange-traded fund that invests only in Indonesian stocks plunged by more than 23% last year as investors shunned the developing nation’s stock market. In the first three months of this year, however, Market Vectors Indonesia Index ETF rebounded, soaring 18%. Another single-country fund, Market Vectors Russia ETF, fell 17% in the first quarter of this year as Russia seized Crimea, a far cry from its 139% gain in 2009.

Single-country emerging-market funds are among the most daring and volatile investments available. The political and economic fortunes of a developing nation can shift dramatically in a very short time.

But these ETFs enable you to benefit from investments in various fast-growing economies that are still too small to be represented in a broader foreign-stock fund. And if you pick the right ones, the payoff can be huge. There now are more than 100 single-country ETFs to choose from.

ETFs with long-term potential…

Market Vectors Vietnam ETF (VNM). Vietnam benefits from the migration of low-end manufacturing out of China, where wages have risen. Policymakers continue to enact economic reforms to attract foreign capital.

iShares MSCI Poland Capped ETF (EPOL). Poland has managed to remain relatively unaffected by euro zone problems because it has its own currency and is able to attract European manufacturers with its skilled workforce and low wages.

iShares MSCI Mexico Capped ETF (EWW). Mexico’s economic growth is improving, and the country is taking more aggressive steps to deter drug trafficking.