Danger Ditch is the first cavern you explore in Pikmin: Near Extinction. This is required to finish in order to complete day one.
To go in you need at least 100 Red Pikmin out. It is in the exact place the engine was,and is easy to spot.
Sublevel 1 is just a short little level. All that it has is 5 Dwarf Bulborbs, and a Red moldy and rotten apple, which is analyzed be the ship to be radiating some sort of wave, and to olimar, is poisonous, which is a warning to things to come.
Sublevel 2 has a more complex design, and has 2 roads that split up. one leads to the Eternal Fuel Dynamo and another hole going further, the other leads to an area blocked by a metal wall, which will be opened by Black Pikmin later in the game, which contains a hole into the dangerous Unknown Lair.
Sublevel 3 has an yellow Onion in it. You can see that there is a huge hole in the ceiling, and that a yellow Pikmin is getting chased by a fiery blowhog. After you defeat the blowhog (Which cannot harm you), you can go to the surface (Via Geyser(The onion will follow you)) and you can break down the electric gate that has pellet posies behind it. You can get the Whimsical Radar that was on a high platform, to end day one.