Tomb of Annihilation Help!!

Hello fellow adventurers, 

I have recently started DMing the Tomb of Annihilation book for a party of 5. The party has not yet entered the jungle (we only had 2 sessions, mostly in the starting port)

I have been really struggling to get my head around the mechanics of the hex crawl.

I can't really seem to understand how the pace that the party chooses affects their journey. 

I understand the navigation, the weather mechanic, random encounters and stuff like that. 

However I can't really understand how pace works or even how the hex-crawl works in general.

Sorry if this seems like a bit of a chaotic thread, but would love for some guidance or tips on how to run this in the best way possible!!

I appreciate any feedback and thank you all 

Here's the basic breakdown

Fast: 50% chance to move an extra hex; -5 to Perception checks for avoiding ambushes or finding clues

Normal: Predicatable speed; no benefits or penalties

Slow: 50% chance to move 1 less hex; lets use Stealth while moving so they have a chance to ambush enemies or avoid them entirely

Thank you for that!

I guess I am still a bit confused on the hex-crawl. 

How does the actual jungle exploration work?

Each day, the players choose their intended direction. One of the players, the designated navigator, will make a Survival check (DC 15 in jungle, 10 by the coast/lakes) to see if they move in the right direction. They get a +5 to this check if they are moving slowly, and a -5 if they are moving fast.

If the check is successful, they move where they chose to go.

If they fail, they get lost and move in a random direction chosen by rolling a D6 (one result for each of the 6 adjoining hexes). If they are lost, you do not tell them which hex they end up on. Once they make a successful Survival check (which may take a couple days), you reveal to them where they are on the map.

If the party chooses, they may want to hire a guide from a town or camp to help them navigate, which is sometimes necessary if there is nobody in the party who is decent at making Survival checks.

Start them at level 1 or 3, don't go past level 5 until they are in Omu. Should be 9 when they enter the tomb.

There's a note (handout 15 from memory) from the company of the yellow banner that they'll find in Omu that describes the entrance of the tomb of the nine gods in the north of the city, it's hard to miss.

You're worrying about the wrong thing, finding Omu is going to be the hard part. There's only a couple people in Chult that know Omu's location, so your party will have to find one of them first and tell them enough for them to be able to reveal the location.