The details shared here apply to the most recent versions of our themes. To keep your theme up to date, check out this helpful document.
In your Collections pages & Featured Collections sections on desktop, you can easily show the secondary image of a product on hover by enabling one of the theme's built-in settings!
Please note: the show secondary product image only applies on desktop as there is no hover functionality on mobile devices.
In order to enable the setting, head into Customize (your theme editor) > Theme Settings > Product Grid.
Within the Product Grid settings, enable the "show secondary product image" option:
Your Collection pages & Featured Collections sections will now display the secondary product image just by hovering over that product image thumbnail.
If you are on a theme that supports Shopify's Product Media functionality, this setting will not display a secondary image on hover if a video is included as a media type in the product gallery. Instead, hovering over the thumbnail will play the video.
To find out if your theme has support for product media, check out this article.