Lost Marbles are something you can find in the different zones you’ll visit during your adventure through Tiny Tina’s Wonderland. Here you’ll be navigated to the Lost Marbles which are scattered around Drowned Abyss.
Lost Marble Location #1 - The Seapulchere
Head to the Dry ‘l’s Gallery Fast Travel and follow the path west until you reach The Seapulchere, then climb up onto the ship and jump over to the platform in the left corner to reach the first Lost Marble.
Lost Marble Location #2 - Temple of Sacrifice
Head to the Dry’l’s Gallery Fast Travel and go up the hill, then take the first right to reach Scuttle Buttress. Continue following the path around until you arrive in Temple of Sacrifice, then take the stairs on the right and proceed through the area to reach the Ancient Obelisk. Here you’ll see a jump pad which you can use to reach some broken wooden platforms, then you’ll find the second Lost Marble to the left.