Currently, in both the mobile and Mac apps, only a single photo can be added to a journal entry. Photos are saved as separate files and displayed above the journal entry to which they’ve been attached.
Multiple photos for a single entry is a highly requested feature. We’re working on an elegant solution, and plan to add support for multi-photo entries in a future update.
For now, we suggest you create more than one entry for a single event for which you wish to include multiple photos. In the mobile app: Once you’ve created these entries, it’s really easy to quickly view all the photos: start by selecting the first entry in the series, then tap the photo to enter the photo viewer. Use the arrows, or swipe the screen left and right, to move from one photo to the next. We plan to add a photo viewer to the Mac app at some point.
Another idea that works well is to create a grid collage with apps like PicFrame, Diptic, FrameArtist, and ScrapPad, then insert the collage into the Day One entry. Both Diptic and FrameArtist have free versions that are more than adequate.
And finally: you can embed photos that you’ve uploaded to a site such as Flickr, with the use of Markdown syntax. There is no limit to the number of embedded photos that can be added to a single journal entry. Please see our Markdown Guide.