How do I enter a new line in a cell in Google Sheets?

When accessing a spreadsheet in Google Drive on a computer with a keyboard, I can enter a new line in a single cell by pressing alt+enter. My keyboard on my Android doesn't even have an alt key. How do I enter a new line on my Android device? For a keyboard on my Android, I'm currently using Swype, but I am assuming, and hoping, there is some kind of general approach that is not specific to a particular keyboard.