This portion of the Luigi’s Mansion 3 guide covers the spectral catch walkthrough which includes all spectral catch gem locations and how to beat the shark boss waiting for you on the boat.
During these objectives, you’ll be given a new tool that will help you get some gems that were previously impossible to collect. Still, it’s recommended to wait until near the end of the game to go back for any gems you may have missed.
Below are the walkthrough sections and objectives. Please note we may have added a few objectives ourselves to indicate the steps you need to take to complete the main objective. Objectives that don’t directly appear on your menu are italicized.
Source: IGN.com Luigi's Mansion 3 Guide: The Spectral Catch Walkthrough