RAAARRRR! Another guide! Yay? Maybe...everyone liked my last one...
Anyway. This guide is going to describe ways to increase your success in drilling EVEN IF YOU'RE NOT A SENSE TYPE. Actually, it should help you ESPECIALLY if you're not a sense type!
- Note to other experienced players: If you want to help by contributing info on map soil types/depths, it would be much appreciated~! ^^
The essentials:
How to drill:
- Talk to Marky** for a free Basic Drill, or buy one from Item Girl.
- Go to your Items panel (hit "i" while not in the chat box)
- Click the drills tab
- Double click a drill, OR drag it to the drill slot on your Equipment panel (hit "e" while not in the chat box)
- Hit "D" while not in the chat box
- Click the ground
**

What drill should you use?
I'm going to source from http://www.mytrickster.net/wiki/index.php/Category:Drill for this section. Feel free to explore the page yourself, as it will have more info.
- Basic Drill - It's good for all types of soil.
Level Requirement: 1
Max Depth: 20m
Life Span: 1300
- Sand Drill (1, 2, 3, 4) - Special purpose drill designed for sand.
Level Requirement: 1/10/30/60
Max Depth: 20m/30m/60m/100m
Life Span: 100
- Land Drill (1, 2, 3, 4) - Special purpose drill designed for grass, land and volcanic areas.
Level Requirement: 1/10/30/60
Max Depth: 20m/30m/60m/100m
Life Span: 100
- Rock Drill (1, 2, 3, 4) - Special purpose drill designed for rock and metal.
Level Requirement: 1/10/30/60
Max Depth: 20m/30m/60m/100m
Life Span: 100
- Green Drill - Special Drill Stage 1. Suitable for hard soils including ordinary brown soil, rocky soil and grass.
Level Requirement: 10
Max Depth: 40m
Life Span: 200
- Blue Drill - 1st Special drill suitable for all kinds of soil. (<<I edited it, because there was a clear translation screw-up...)
Level Requirement: 10
Max Depth: 80m
Life Span: 100
- Yellow Drill - 2nd special drill. Proper for all kinds of soils.
Level Requirement: 20
Max Depth: 120m
Life Span: 80
- Pink Drill - 2nd Grade drill special proper for wet soil like deep-sea sedimentary soil and clay soil.
Level Requirement: 30
Max Depth: 60m
Life Span: 100
- Cleaner Drill - 1st grade drill proper for soil like sand.
Level Requirement: 20
Max Depth: 30m
Life Span: 300
- Blend Drill - 1st grade drill proper for wet soil like deep-sea sedimentary soil and clay soil.
Level Requirement: 20
Max Depth: 30m
Life Span: 300
- Multi-Point Drill - 1st grade drill proper for thick soil like usual yellow soil, rock soil, and grass.
Level Requirement: 20
Max Depth: 30m
Life Span: 300
- Tornado Drill - 2nd grade drill proper for fragil soil like sand.
Level Requirement: 40
Max Depth: 60m
Life Span: 400
- Jet-pump Drill - 2nd grade drill proper for wet soil like deep-sea sedimentary soil and clay soil.
Level Requirement: 40
Max Depth: 60m
Life Span: 400
- Multi-Pistol Drill - 2nd grade drill proper for think soil like usual yellow soil, rock soil and grass.
Level Requirement: 40
Max Depth: 60m
Life Span: 400
- Diamond Drill - 3rd grade drill proper for thick soil like usual yellow soil, rock soil and grass.
Level Requirement: 60
Max Depth: 90m
Life Span: 900
- Chaos Drill - Ultimate drill proper for stone tiles, wood board and artificial floor.
Level Requirement: 80
Max Depth: 120m
Life Span: 600
- Musume Drill - Luxury handcrafted drill made by Sigujilly, the craftsman in drill industry. Good for yellow soil.
Level Requirement: 50
Max Depth: 150m
Life Span: 200
- Gao Drill - Handcrafted drill made by Mr. Gyujang, the craftsman in drill industry. Good for artificial soil.
Level Requirement: 50
Max Depth: 180m
Life Span: 150
That's all well and good, right? But how do you know what kind of soil is what? Well, no offense, but I hope that to some degree, you can tell just by looking. I mean, grass is obviously grass, dirt is obviously dirt, sand is obviously sand, and so on. But there are a few areas that can be tricky to figure out. So for simplicity sake, I will just go through and list as many as I can.
Coral Fields
10m max depth
Loose/Fragile soil. SAND.
Land/GRASS.
Wood boards. ARTIFICIAL.
Dark Cave
20m max depth
Just like mines, caves have a strange soil type. It's both ROCK and ARTIFICIAL.
Desert Beach Fields
10m max depth
SAND.

Land/GRASS.
Wood boards. ARTIFICIAL.
Pyramid Dungeon
20m max depth (Excluding Tut...I need to know the depth at Tut. ^^)
Don't be fooled. It looks like tiles, but is actually SAND.
Crystal Copper Mine
20m max depth
Mines have a strange soil type. It's both ROCK and ARTIFICIAL.
Emerald Forest
20m max depth EXCEPT for Northwest Forest, which has 50m
Land/DIRT.
Land/GRASS.
Poppuri Dungeon
30m max depth
Land/GRASS.
Mud/Sedimentary. WET SOIL. (Yeah, they throw you for a loop with that one. Sticking in puddles that are a different soil type!)
Caballa Relics Fields
40m max depth
Land/DIRT.
Stone tiles. ARTIFICIAL.
Land/GRASS.
Caballa Dungeon
60m max depth, including Tombeth.
Land/DIRT and GRASS.
Stone tiles. ARTIFICIAL.
Jade Steel Mine
130m max depth.
Mines have a strange soil type. It's both ROCK and ARTIFICIAL.
Swamp Fields
40m max depth EXCEPT in the "Maze of Forest" fields, which have 120m, and Tenterlion, which has 200m max.
Land/GRASS.
For some reason, the lily pads count as WET SOIL.
Swamp Dungeon
120m max depth EXCEPT on floor 5, which is 250m max.
Clay soil/Sedimentary. WET SOIL. (Some parts may count as GRASS too.)
Silver Jewel Mine
160m max depth
Mines have a strange soil type. It's both ROCK and ARTIFICIAL.
Warf Fields
80m max depth

Stone tiles. ARTIFICIAL
Metal. ARTIFICIAL.

Asphalt/ROCK. Also ARTIFICIAL.
Wood boards. ARTIFICIAL.
Land/GRASS.
It looks like water, but it counts as ROCK or ARTIFICIAL.
Path to Mermaid Palace
80m max depth
Just like mines, caves have a strange soil type. It's both ROCK and ARTIFICIAL. Path to Mermaid might also count as DEEP-SEA SOIL.
Phantom School
50m max depth on F1 and F2, 80m max depth on F3, 120m max depth in the Annex and Mad Ray.

Stone tiles. ARTIFICIAL.

Wood boards. ARTIFICIAL.
Vines and leaves/Land/GRASS.
Rose Garden
80m max depth
Stone tiles. ARTIFICIAL.
Land/GRASS.
Wood boards. ARTIFICIAL.
Vamp Dungeon
80m max depth, with 60m max at Count Blood.
Carpet/Stone tiles. ARTICIFIAL.
Mermaid Fields
80m max depth
DEEP SEA SEDIMENT.
Shell/Stone tiles. ARTIFICIAL.
Mermaid Dungeon
100m max depth

Stone tiles. ARTIFICIAL.
Mirage Island
80m max depth
Land/DIRT.
Land/GRASS.
Wood boards. ARTIFICIAL.
SAND.

ROCK. Might also be artificial, I'm not totally sure.
Mirage Dungeon
100m max depth
DEEP SEA SEDIMENT.
Snow Fields
120m max depth
SNOW.
Ice/SNOW.
Ice Dungeon
180m max depth, except at Odinea, which has 200m max.
Ice/SNOW
Precious Jewel Mine
200m max depth
Mines have a strange soil type. It's both ROCK and ARTIFICIAL.
Techichi Volcano
180m max depth, except at Soki, which has 200m max.
Volcanic ash/Land/DIRT.

Volcanic ash/Land/DIRT and possibly ROCK.
Wood boards. ARTIFICIAL.
Tapasco Volcano
150m max depth, 250m max at Spicy
Volcanic ROCK.
Cherry Blossom Fields
20m max depth
Land/DIRT.
Land/GRASS.
Stone tile. ARTIFICIAL.

Rugs and cushions. ARTIFICIAL.