The structure of an ETF is so flexible that many money managers have formed ETFs to invest in just about any corner of the transportation industry. Whether your interest is in airlines, shipping, freight, or rail you can invest in a specialized ETF for it.

If you want to invest in the shipping sector, consider investing in a shipping ETF. SEA is a shipping ETF that provides an investor with some diversification since the investment is spread among multiple companies in the shipping industry.

You can buy shares of a shipping ETF in your brokerage account or individual retirement account (IRA). Because exchange-traded funds are different from mutual funds, prices of ETF shares fluctuate during the day as the shares are traded on stock exchanges. Depending on the perceived value of an ETF security's holdings and the consequent investor demand for the shares, prices may move up or down during the day just like stock prices.