Dividends and diversification -- those two things can help you achieve a comfortable retirement when combined with the income you will receive from Social Security.

One way to obtain both dividends and diversification is to invest in exchange-traded funds (ETFs) that own baskets of dividend stocks. These three dividend ETFs fit the bill nicely.

1. SPDR S&P Global Dividend ETF

State Street's SPDR S&P Global Dividend ETF (WDIV -0.12%) offers an easy way to invest in a large number of global companies with high dividend yields. Even better, the ETF looks for companies that have increased or maintained their dividends for at least 10 consecutive years.

The SPDR S&P Global Dividend ETF owns 100 stocks. No single country can have more than 20 stocks in the ETF. No sector can make up more than 25% of its holdings. Also, the maximum weight any stock may have in the portfolio is 3%. Currently, the stock with the highest weight only accounts for 1.58% of the portfolio's value.

State Street launched the ETF in May 2013. Since then, its net asset value has increased by an annualized average of 4.35%.  

This ETF currently offers a 30-day SEC dividend yield (a standardized annual yield that uses net investment income over the last 30 days) of 4.78%. The main drawback of the SPDR S&P Global Dividend ETF is its relatively high expense ratio of 0.4%.

2. Vanguard International High Dividend Yield Fund

Vanguard markets several dividend ETFs that retirees might like. Its Vanguard International High Dividend Yield Fund (VYMI -0.37%) especially stands out. As its name indicates, this ETF provides exposure to international stocks that are expected to pay above-average yields.

The Vanguard International High Dividend Yield Fund currently owns 1,302 stocks. It focuses on large-cap value stocks. The median market cap of companies in its portfolio is $43.2 billion, and they have an average price-to-earnings ratio of 9.0. The fund's top holdings now include Shell, Roche, Novartis, Toyota, and HSBC.

While the Vanguard International High Dividend Yield Fund has higher risk than some ETFs, it also offers a higher potential for returns. Its net asset value has increased by an annualized average of 7.14% since it was launched in February 2016.

The ETF's yield stands at 4.53% right now. Its expense ratio is 0.22%, which is higher than several of Vanguard's ETFs but lower than the other dividend ETFs on our list.

3. Invesco S&P 500 High Dividend Low Volatility ETF

Retirees love high dividend yields and low volatility. Invesco operates an ETF that aims to provide both -- the Invesco S&P 500 High Dividend Low Volatility ETF (SPHD 0.41%). 

This ETF holds around 50  S&P 500 components that have above-average dividend yields and track records of low volatility. Its portfolio focuses largely on large-cap and mid-cap value stocks. Current top holdings include AT&T, Altria Group, Verizon Communications, and Kinder Morgan.

Invesco first offered the ETF in October 2012. Since then, it has delivered average annual net asset value growth of 9.13%.

The ETF's SEC 30-day dividend yield currently stands at 4.59%. Its expense ratio is 0.3%.