The Trident Mask & Fin Keeper gives you a way to clip mask and fins together for the walk to the water or while organizing equipment on a boat. Its nylon webbing, two quick-release buckles, and wire-gate clip make it easy to attach the bundle to a suitable point.
The source lists black and blue options. Confirm the selected color and check that the clip and attachment location will keep gear secure without creating a snag hazard during diving.