Atlantic offers a "subcollections" feature which groups collections together for improved access and organization. Once this feature is set up, your Subcollections page will resemble a custom Collections list page featuring a select group of collections, each displayed as a Subcollection.
Use the Collections admin to create the landing page for your subcollections, then the Navigation admin to organize the subcollections using a navigation menu, and then customize subcollections in the theme editor.
Create the landing page for your subcollections
Navigate to Collections (Products > Collections), then Create collection. This collection will be the landing page for your subcollections, so the title should reflect the general theme or category of the subcollections. For this example, 'Artwork' is the title of the Collection.
Once you have added a Title, configure the Collection type to Manual. In the bottom-right corner, locate the Theme templates box to select the collection.subcollection-list template, and Save. This will only appear if Atlantic v13.3.5 or higher is in the published position in your Online Store.
Before leaving this new collection's settings, scroll down to the Search engine listing preview, then select Edit website SEO.
No edits are required here, but the end of the URL is needed for the next setup portion. In the URL and handle field, copy the end of the URL (the handle) to your clipboard. In this example, 'artwork' would be copied.
Organize the subcollections using a navigation menu
The next step for setting up subcollections is in the Navigation settings. Go to Online Store > Navigation and select Add menu.
Shopify includes pre-made menus for Main Menu and Footer Menu, but these should not be used for the subcollections setup, as the handles for these menus cannot be edited.
Match the collection and menu handles
First off, insert the Handle (copied from the collection's URL) into the right-side field. The Title of the menu is not as important as the Handle, so the Title can be anything, but the Handle must match the collection's URL.
Add subcollections as menu items
Once those fields are filled, start adding some menu items by selecting Add menu item. These menu items will serve as the subcollection links, so in this example, the Prints, Sketches, and Postcards collections have been added as menu items.
Add more menu items with the desired collections linked, then Save.
Customizing subcollections in theme editor
The final step takes place in the theme editor, so leave the Navigation settings to open the theme editor (Customize).
Open Collections, then the subcollection-list template with the page selector. Open Sub-collections list page in the left sidebar.
Show breadcrumb links
Enable Show breadcrumbs to activate this feature. Breadcrumbs are secondary navigation links that reflect the current page and how the customer got there.
Display collection image
Enable Show collection image to include the collection image at the top of the collection page.
For more information on collection images, check out Shopify's article.
Select Product showcase, Collection list, or Menu list for the Layout option.