Well this is my guide for Nautilus I am New to making guide I hope you like it.
I build him differently to others you can solo any tanky AP nautilus with no problem.

Nautilus, The Titan of the Depths.

Statistics
Health 432 (+86)
Health regen. 7.45 (+0.55)
Mana 200 (+50)
Mana regen. 7.45 (+0.7)
Attack damage 52 (+3.3)
Attack speed 0.613 (+0.98%)
Armor 12 (+3.25)
Magic res. 30 (+1.25)
Range 175
Mov. speed 300


Staggering Blow

(Innate): Nautilus' basic attacks deal an additional 2 + (6 × level) physical damage and immobilize his target for 0.5 / 0.75 / 1 seconds.
This effect cannot trigger on the same target more than once every 12 seconds.

Dredge Line
(Active): Nautilus hurls his anchor forward. If it hits an enemy unit, Nautilus drags himself and the target together dealing magic damage and stunning them briefly. If the anchor hits terrain, Nautilus will drag himself forward and the cooldown is reduced by 50%.
Range: 950

Cost: 60 / 70 / 80 / 90 / 100 mana
Cooldown: 14 / 13 / 12 / 11 / 10 seconds

Magic Damage: 80 / 120 / 160 / 200 / 240 (+0.75 per ability power)

Titan's Wrath
(Active): Nautilus surrounds himself with dark energies, shielding him from damage for up to 10 seconds. While the shield persists, Nautilus' basic attacks apply a damage over time effect to all units around his target, dealing damage over 2 seconds.
Cost: 80 mana
Range: 350

Cooldown: 26 / 24 / 22 / 20 / 18 seconds
Magic Damage: 30 / 60 / 90 / 120 / 150 (+0.4 per ability power)

Shield Amount: 80 / 130 / 180 / 230 / 280 (+10% of bonus health)

Riptide

(Active): Nautilus slams the ground, causing the earth to explode around him in 3 waves. Each explosion deals magic damage to units in the area and slows them for 2 seconds. This slow diminishes over time.
A unit can be hit by more than one explosion, but they take 50% less damage from additional explosions.
Cooldown: 10 seconds
Range: 400

Cost: 60 / 70 / 80 / 90 / 100 mana
Magic Damage: 60 / 100 / 140 / 180 / 220 (+0.5 per ability power)

Max Magic Damage: 120 / 200 / 280 / 360 / 440 (+1 per ability power)

Slow Amount: 30 / 35 / 40 / 45 / 50%

Depth Charge

(Active): Nautilus fires a shockwave that chases an enemy champion. This deals magic damage to enemies it passes through and knocks them into the air.
The shockwave explodes upon hitting its target dealing magic damage, launching them into the air and stunning them.
Cost: 100 mana
Range: 850

Cooldown: 120 / 100 / 80 seconds
Pass Through Magic Damage: 125 / 175 / 225 (+0.4 per ability power)

Explosion Magic Damage: 250 / 350 / 450 (+0.8 per ability power)

Stun Duration: 1 / 1.5 / 2 seconds

Lore

Once, Nautilus was a sailor commissioned by the Institute of War to explore the uncharted reaches of the Guardian’s Sea. This expedition took him deep into unknown waters where he and his crew found a vast section of the ocean’s rich blue waves were replaced by a black, oozing liquid that none of the crew could identify. Though their job was to investigate anything new that they found, no man aboard was willing to brave the murk except Nautilus. Only moments after he donned the hulking diver’s suit and climbed over the ship’s rail, something lurking in the muck grabbed hold of him. He clung to the side of the ship, but the thing below pulled him fiercely, rocking the entire ship. The other sailors grew afraid and made a terrible decision. As he stared and pled for help, they wrenched his grip free of the rail. He tumbled to the ink, grabbing the anchor in futile desperation. As he sank, he could do nothing but watch as the dark outline of his ship faded away. Then everything went black.
When Nautilus awoke, he was something different. The great iron suit was now somehow part of him, he could not tell where it ended and he began. All the details of his memory were fuzzy and indistinct but one fact remained clear: he was left here, alone in the sunless depths, to die. In his hands he still clutched the anchor that belonged to the men who had condemned him. Having no other purpose, he took this clue and trudged - too heavy to swim or run – in search of answers. He wandered without direction or sense of passing time in what felt like an eternal dream. By the time he stumbled upon the shores of Bilgewater, he could find no traces of the man he was. No house, no family, no life to which he could return. Terrified sailors who’d heard his tale directed Nautilus back to the Institute, but the summoners refused to relinquish the names of the others they commissioned. By then Nautilus had learned about the League of Legends and there he saw an opportunity to discover and punish those responsible for the time and life he lost.

"When lost in utter darkness, there is nothing left but forward."
Nautilus

Pros

Hard to kill because of being tanky.
Easy jungle.
Good damage output.
Ganking is easy if you can land your Q.
Lots of CC.
Dredge Line can be used to save your life and others.
Ult have very good cc and chances them down no matter what.
Good passive in my opinion.
Very good farmer.


Cons

Cant gank till lvl 4.
Cool downs are kinda high.
Mana cost is high as well

The runes I build on him make him tanky and fast so you can chase down the enemy and take a few hits. I have mana regen as well because he is very mana dependent and if you lose you blue some how you can still jungle.

I have decided to build nautlius as a tank taking the masteries 0/21/9. The increased buff duration allows him to jungle more efficiently for an extended period of time. This in turn allows for faster levels and an increased damage output early game.

I start his build with cloth armour and 5 health potions instead of the commonly used jungle build of regrowth pendant and one pot. I have tried both builds and the latter doesn't seem to work as efficiently. After you have finished building Trinity Force, make a decision on whether it is worth building magic reduction or armour depending on what their main damage output is. Build a Force of Nature or Randuin's Omen depending on the point above. Finally, replace your wriggle's Lantern with Madred's Bloodrazor to increase damage. Finish your build with pots for that extra buff late game.

MAKE SURE TO WARD!!!

I build him W.E.W.Q then max W first then max your E at lvl 13. His W is his main source of damage output out of all his spells and gives him more HP you take Q at lvl 4 so you are able to gank. Take your ult at lvl 6/11/16.

I take Smite for the jungle as it is impossible to jungle him with out it, it also stop your buffs being stolen of you get ganked at your buffs, Dragon or Barron.

Flash is very good if they are to far out of your range for your Q or your R and you can also Flash and stun with your passive.

You could also take ghost for chase down but you are faster then most others champions because of your movement speed quits and your item build.

Start at blue buff. Get mid to leash and bot or top lane to damage it for you depending on which side of the map you are on. Use smite to finish it off and get you to level 2. You should then head to wolves, then wraiths, then double golems, which will leave you at level 3. You should have enough health to take red buff (with smite), and then wraiths. Check for ganks, and if none are available, continue jungling.

Yellow dot is wriggles ward on enemy's blue.
Green dot is normal wards.
Pink is pink wards.

When ganking At lvl 4 if they don't have spell Shield activate your W Hit them with your Q auto them for passive then slow with E and reactivate your W as soon as its off cool down when fighting.

If they have a spell shield like Nocturne and Siver try to get them to waste it before you Q them.

Ganking at lvl 6+ do not start with your R because it has a longer range then your Q use it after they start to run.

You are a jungler so you wont be farming till mid - late game. Nautilus is a very good farmer activate your W then E and the AOE from your W's autos will kill all the creep very fast.

Thank you for checking out my build. Please rate and comment and post pics on how it played out for you. Again this is my very first guide and it seems to work very well.

Thank you to:
Gauky.
JuicePopper.
Whisk.