*Warning: If you are one of my players, then do not read this*

OK, this post may be kinda long and sorry about the boring (but neccesary backstory) but here we go:

So, I love playing hags in D&D, I can do an excellent hag impression and I love making a hag voice. I like hags so much, I even tried to make my DDB username 'Hag', but it was already taken. 

My players know me well, and know that I love putting hags in 5e. They even became suspicious of a disguised hag just because she was called 'Auntie Cathindra" (her full name is Auntie Cathindra Cacklebones, but I didn't tell my players that).

I want to (in the distant future), get the characters on an independant island resort called Tropicana. Here's the backstory for the island:

"After the tyrant Azur (the blue dragon BBEG for my campaign and once ruler of the whole world) was defeated (he still lives), his old allies and servants remained, hidden on Tropicana. The three strongest spellcasters on the island (A human sorceress and master of water named Marzisa, a dwarven wizard of ice and snow named Razana, and a druid of the forest named Flora) came together to expose the leaders and commanders that were once under Azur and trying to help with his evil machinations. After there crucial role for the forces of good, the sisters were each crowned queens (dictaters) of 1/3 of Tropicana. The sisters have ruled for hundreds of years now and each turned their section into varius tourist attractions."

The spellcasters are all disguised hags and sisters who were and still are serving Azur (they are in a coven). They turned in the other (less important) lieutenents of Azur so that they could save their own lives. They pretend to be rivals but really (though their own resort/tourist attractions do compete with each other) give all their money to Azur and do all he asks (in return to... we'll explain that later) including killing his opponents (the PC's).

In the deal with the hags, Azur's part of the bargain was making it so that any soul dieing on Tropicana due to unnatural causes, is given to the hag most responsible for their death. Each hag has a third of Tropicana, and their "tourist attraction" is really deadly.

Marzisa (sea hag): Rules over the land of magical water springs, and nice weather.

Activities: Playing, relaxing, in the springs.

Dangers: Many of the springs are minorly poisonous (for some reason you have a level of exhaustion)! In addition, it is fully of loads of deadly sea monsters.

Razana (Bheur Hag): Rules over the land of snow and ice.

Activities: Skiing, hiking snowy mountains, snow sports.

Dangers: Yetis, incredibly steep, 3 quadrillion feet high mountains.

Flora (green hag): Rules over the land of forests and greenery:

Activities: Forest hiking, zoo.

Dangers: Zoo animals super dangerous cages not secure, posoinous fungi all over the forest.

My question:

How do I disguise the dangers of Tropicana (when people are bound to say everyone on Tropicana dissapears, even if it is hushed up), the hags' identity (when my players know I love hags and are good at sensing when someone is one), and get my players to keep doing the activities on Tropicana (at least long enough for the Hags to realize Azur wants them dead and send assasins)?

Would any PC believe the dangers on Tropicana are accidents, and how would the NPC's convince them of that?

BTW: Nobody (well almost nobody) lives on Tropicana, you visit, you probably die.

Edit: I'm gonna use some things Solarsyphon reccomended and make it so not every who visits dies. Thanks to him for his excellent ideas.

Thank you for bearing with this way to long post and helping me out. I really appreciate it.

Step 1 - Post the question in the Dungeon Master's forum where players are less likely to notice.

LOL, I've told my players to avoid going to this forum (none of them have DDB accounts, but one sometimes browses forums).

Edit: I followed your advice and moved it.

Hag magic is weird, like literally by definition is unique and functions distinct and seemingly without rules at times. 

I see no reason why they can't have enchanted the island with a high level illusion magic, something like Mirage Arcane, that can only be seen through with truesight or by fulfilling some sort of criteria to be able to see through the illusion. You could just describe it as a paradise that is like a totally normal vacation spot with other people who are happy and what not and when the players aren't getting the benefits of a long rest because the food they ate was rotten, or subtle other things that they would take for granted don't seem to be working, then they would start noticing that something is wrong and by then you've already sold the place. 

Maybe take a page from the Scooby-Doo doo live action movie for how things may be kept hush hush.

The basic problem with getting players to believe things are accidents is that players assume anything happening 'on screen' must be significant and are thus disinclined to believe in accidents. Rather than trying to get them to believe in accidents, perhaps come up with a red herring that can be blamed?

Hmmm. I could have a group of 'rebels' who know the hags are trying to murder visitors for one reason or another. The hags could say that the rebels served the BBEG Azur, and are causing all the problems. Do you think that would work?

Generally there are a few ways to hide something: 

False ends: Think of things they might do to detect a hag and create a misleading result. For example they may be enchanted to appear non magical or as a different creature type. 

Red herrings : Add other options for culprits. Maybe other non hag witches or even other hags are in the area. Maybe they took on a human student and have used curses to make them unwittingly do their bidding. 

False clues: There could be misleading rumors like hauntings of certain buildings. The return of the ghost of the dragon or  something similar 

To hide the dangers specifically I wouldn't make it so that everyone who visits dies. For it to remain a tourist attraction, most people must survive and it must look like the hags are doing what they can to make it as safe as possible.  My advice would be to have the hags put up warnings and have the people who die break them. 

Some other misc tactics;

• The sea witch tries to attract the sick and elderly who are likely to die any way with rumors of healing waters and offers of medical care. The waters do indeed make people feel better encouraging them to stay but in fact accelerate the rate in which these diseases progress.  Maybe they suppress the effects of a disease and curse for a certain amount of time but during that time you automatically fail any saving throw you might make to stop the disease progressing. 
• One of the hags has closed a location claiming it is dangerous but they have also spread rumors of treasure or mystery there to attract people to enter. Inside is a monster like a ghost or yeti.
• The forest has a strict rules of not leaving the path but deep in the woods there are will o' wisps or sirens that attract people from the path with their bright lights and charming singing. 
• In the sea witches lair there is a captain who lost his leg battling a sea monster like a large shark. Attacks are rare but he lost his whole crew trying to track it down for revenge.  The witches offer a large bounty for the creature  claiming to fear its dangerous but it is actually a trap to lure adventurers to their death. 
• One of the mountains in the snow hags lair is consider one of the tallest in the world people often attempt to climb it but the climb is extremely dangerous and rescue almost impossible. Several explorers have perished attempting to climb it.  In fact no one has successfully climbed the mountain as it requires magic to stop you from suffocating at high altitudes and the rumors of people succeeding are spread by the hag. 

OMG! Thank you, this is awesome and I definitely will be using it!

One way of hiding things (and giving the PCs an interesting side mystery) is that that people who die at the resort get replaced by faerie changelings (could be doppelgangers, could be a construct of some sort), which return home and then fake their deaths (or, for constructs, just dies).

Quote from Pantagruel666 >>

One way of hiding things (and giving the PCs an interesting side mystery) is that that people who die at the resort get replaced by faerie changelings (could be doppelgangers, could be a construct of some sort), which return home and then fake their deaths (or, for constructs, just dies).

 Maybe they are targeting people to replace.  

A side idea would be if the pcs start talking too loudly about the strangeness they get confront by a Cadre of lawyers for defamation or whathaveyou.

Quote from Pantagruel666 >>

One way of hiding things (and giving the PCs an interesting side mystery) is that that people who die at the resort get replaced by faerie changelings (could be doppelgangers, could be a construct of some sort), which return home and then fake their deaths (or, for constructs, just dies).

 I also really like the bodytaker plant and podling for that. You could easily have  a village of podlings form people who came to visit and now never want to leave. 

Quote from HeroZero >>

Quote from Pantagruel666 >>

One way of hiding things (and giving the PCs an interesting side mystery) is that that people who die at the resort get replaced by faerie changelings (could be doppelgangers, could be a construct of some sort), which return home and then fake their deaths (or, for constructs, just dies).

 Maybe they are targeting people to replace.  

A side idea would be if the pcs start talking too loudly about the strangeness they get confront by a Cadre of lawyers for defamation or whathaveyou.

 The idea that part of the places popularity and hidden deaths is from a few well placed doppelganger monsters is cool too.  It doesn't need to be  world domination or even to fake deaths just a couple as part of small plots would do. 

How about having some of the visitors be long term visitors, they don't want to stay there but are bound for some reason. This could be something like blackmail, any of the visitors that go there to escape something from back home (maybe they commited a murder?) the Hags know about it and say they can live there but must not disclose any secret. Then you have a number of NPCs saying the place is fine, explaining that people dying are just accidents, but theres a chance the players can intimidate or question the NPCs to find the truth. In return to the hags, these NPCs look after certain things in the resort, whether it be working the kitchens, tending the grounds, or assuring that "accidents" happen to keep the sea creatures fed.

You need to mix in with that some NPCs who are genuinely there though with no idea of the true goings on, then it's not obvious that everyone quizzed knows something.

If you have access to the candlekeep mysteries book, check out The Price of Beauty adventure which is about a health spa resort run by 3 hags, each of which know part of a process to make peoples vain desires reality. Youtube has play throughs and reviews of the adventure if you can't source the book.

Part of my inspiration came from that adventure. I'm a big fan of Aerois and Nights of Eveningstar (Mark Hulmes wrote Price of Beauty and DM's the shows I mentioned).

PS. Thanks for the help.

Who said that hags HAVE to be women? Make them men. Your experienced players will never suspect that. 

if you want to really mess with them, have them pull the “damsel in distress” routine only they’re men who are being held captive by women away from the island. And they “need” to be rescued and then ask the party to escort them home where they can enjoy their old age and retirement in peace and quiet. Home being the island of course. 

They become 3 men and a baby.

Most lore does state that hags are female, but yea in a game where you make the rules, maybe they could be male. Or if still sticking to true lore, the hags could be disguised as males using an illusionary spell, with a fourth person thrown in for good measure which could be some kind of demon or something working with the coven. That removes the 3 people in charge assumption of them being a coven of hags.

Especially when you have experienced players who are expecting hags and are looking at every woman and assuming that she’s a hag because the DM loves hags so much. 

Great idea! I'm now gonna have the hags using their illusion magic to pretend to be men.

PS. Please keep up the good work guys! It's really helpful and means a lot.

Quote from BoringBard >>

Great idea! I'm now gonna have the hags using their illusion magic to pretend to be men.

PS. Please keep up the good work guys! It's really helpful and means a lot.

That does lend itself to some comedy moments though, ok I know gender stereotype isn't all the rage these days but this is D&D where stereotyping is rife, having the men have feminine quirks as very subtle clues could be quite fun. They have floral furniture or they always go to the toilet sitting down (not sure how that would make its way into the adventure?), but you get the idea...