30 FEET LONG?!

Is that really necessary?

Yes. Yes it is. 

Honestly it's a little small.

Megalodon can grow to be upwards of 50 feet long.

True this is only about the size of a decent sized great white

We are gonna need a bigger boat....

Quote from kirkchristensen >>

We are gonna need a bigger boat....

 I would like to report this comment for being awesome.

Quote from taven03 >>

True this is only about the size of a decent sized great white

 I'm sorry but the size of a great white is 12-21ft with a large one being maybe 25ft. 

This is a large shark but I agree with the under laying sentiment that it is a bit small for what a "Giant" shark would be. 

Shouldn’t it be 15 ft long? 30 feet would be gargantuan, it says its size huge

The makers of these fine monsters need to do a little reading. For starters, they should reference Steve Alten's awesome Meg series. Angel is something on the order of 70' long...

I'm going to modify these stats heavily, but I need a colossal shark for my session tonight: Jaws meets 20,000 Leagues Under the Sea.

Quote from Samso1 >>

Shouldn’t it be 15 ft long? 30 feet would be gargantuan, it says its size huge

 Creature size isn't indicative of the actual size, rather the space it controls in combat. I assume the tail isn't too useful for manipulating an area.

Quote from ClericalKenku >>

Quote from Samso1 >>

Shouldn’t it be 15 ft long? 30 feet would be gargantuan, it says its size huge

 Creature size isn't indicative of the actual size, rather the space it controls in combat. I assume the tail isn't too useful for manipulating an area.

 You should check out Thresher sharks. Tall skinny tail fin that they use to 'slap' an area and stun their prey.

Quote from ClericalKenku >>

Quote from Samso1 >>

Shouldn’t it be 15 ft long? 30 feet would be gargantuan, it says its size huge

 Creature size isn't indicative of the actual size, rather the space it controls in combat. I assume the tail isn't too useful for manipulating an area.

 That is correct, size is determined by how much space a creature occupies. Also, here's the link for creature sizes relative to the space it occupies on a board: https://www.dndbeyond.com/sources/basic-rules/monsters#Size

Creatures that are within certain heights/length limits are usually classified as medium, large, huge, etc:

Tiny creatures are, as the name suggests, extremely small. They are about 2 feet or less (these include Imps and Faerie Dragons). Meanwhile, Small creatures like Goblins are about 2-4 feet in height or length. Medium creatures are 4-8 feet long (Dwarves at around 4, Goliaths and Firbolgs at 8 for some examples). Large creatures like Trolls and Ogres are about 8-16 feet tall, and Huge creatures (like our 30 foot shark here) are about 16-32 feet. Gargantuan creatures are at least over 32 feet, and most, like Ancient Dragons, are well past that. Gargantuan creatures even occupy 20x20 feet an a regular DND board, whereas regular Medium sized PC's are at the normal 5x5. 

yes

Megalodon would be a gargantuan creature and likely a CR 8-10, as it's 50-59 feet long and sperm whales are a similar size and CR 8.

*Ahem* "you're" gonna need a bigger boat. ;P

I've got some great memories with the giant shark. My Halfling sorcerer polymorphed into a giant shark to fight a red dragon at a underwater world. The dragon didn't have a change to survive... 

Use this with some Sahuagin for a really awesome sea encounter.

Yup! :)