Hello there.
This is my nami jungle guide. I know all you need to know about this. I am pro at it. Even though I don't even own nami, I went 3-0 with her in normals in the jungle so im practically a nami jungle god. Don't believe me? I defeated a diamond 5 sion with nami jungle. This guide will teach you how to be a god with nami in the jungle.

These are standard AP Mid runes. Nami needs that ap damage. You're in the jungle now, not support, so you don't need any support/tank runes.

This is pretty simple. 21 in offense for more ap damage and 9 in utility to help you with clears in the jungle because the jungle is not your friend until post level 6.

This is pretty basic and self explanatory as well

Magus Enchantment - AP and Cooldown
Sorcerer's Boots - Magic Penetration + Movement speed
Lich Bane - Your main source of damage is e empowered autos : lich bane will amplify this
Ludens - For more burst/AOE
Deathcap - More ap the better
Void staff - For magic penetration in late game

You ult take propriety just like any other champion. Then you max e for easier clears as well as damage. You max q next for more damage. w is last because ,remember, your not support anymore.

Flash to get away
Smite for jungle
Pretty self explanatory

The great thing about nami jungle is now one expects it, not even your teammates.
She is such a WTF in the jungle that you get the upper hand by taking your enemies by surprise.
Use your ocean (Your ult) wisely and scare your opponents with a random wave out of nowhere.
You can use e to empower yourself or your teammates, basically meaning your like an mage and a support at the same time. Though you are not support, you can still play the support role, just not with support items because who needs those.

OBVIOUS NOTE: Nami is good at kiting, use this.

Play nami jungle in ranked. Its basically freelo and I would know because I have played her in the jungle twice already in normals.

Pro:
Such surprise
Much Damage
Ocean
Just plain op
Much kite
Support and Mage

Con:
Horrible first clear
Not a tank

You need a hard leash from your lanes.
It might be wise to start at a buff instead of gromp/ krugs,
Once you get through 1-2 clears, it should be alright then

Your role is to cc everyone. Use your ult and q to turn fights around or disengage.
Use w to heal your teammates and e to do more damage. This has been repeated throughout this guide but I'll emphasize it again: You are both a mage and support.
Also be sure to kite your opponents.

Ocean in jungle is op. Send salt to your enemies and teammates alike!