To get to Second Sea, it's necessary to talk to the Dimensional Sailor, who is looking for something called a Poneglyph Scroll. Although it's a very well-hidden item, it doesn't take long at all to collect. There are plenty of new items to collect in Second Sea, including 3 Sword Style, so it's definitely a good idea to grab the Poneglyph Scroll when possible.
Poneglyph Scroll location in Haze Piece - Roblox
It's impossible to get to Second Sea in Haze Piece without reaching level 2200, so that should be step one. After reaching this level, talk to the Dimensional Sailor. He is in Starter Island, at the edge of the dock where the Boat Merchant is.
During the conversation, he will ask for something called a Poneglyph Scroll. Fortunately, it's not too far away—it's just off to the side in the Rocky Pillars, which is located just west of Starter Island.
Once inside, look for the pillar that is dead set in the middle of the lake. At the top of this pillar will be a black box. This will be difficult to see since the pillars are all dark to begin with, but basically you will want to see if you can find a darker box near the top of the pillar.
You can actually go inside here and find the Poneglyph itself. Interact with it to collect the Poneglyph Scroll. Take that scroll to the Dimensional Sailor to get to Second Sea.
I highly recommend using a fruit that gives a flight ability (Flame, Electricity, etc.) I tried getting up the pillar with just jumping, and it was not successful.
Want more Haze Piece guides? Pro Game Guides has you covered with How to get Devil Fruits in Haze Piece – Roblox.