Create-A-Sim
Two new hairstyles for females.
Two new outfits for females, one of them can also be worn as swimwear.
New straw hat for males
Sarong outfit for males.
General
Almost all rabbitholes are new, except the mausoleum. Some of the rabbit holes have straw roofs, but sadly the world does not give us straw roofs.
The new criminal warehouse is an awesome looking pirate cave!
Family the Pleasants are back from the Sims 2
Build & Buy Mode
New plants and trees
New flower display object.
New streetlight.
A Decorative Starfish.
Flower shaped floating pool lights.
Freezer bunny Tiki columns.
New double bed.
New fruit sculpture.
New mailbox.
New wedding arch. *might only be available in gold edition*
New hot tub. *might only be available in gold edition*
New curtains. *might only be available in gold edition*
New aquarium. *might only be available in gold edition*
Decorative spa shelf. *might only be available in gold edition*
New rocks for world building.
Premium Content
New Sauna Premium Content that gives a new refreshed (+25) moodlet
Sims can woohoo in Sauna, they get hidden in steam during it. Can also try for girl or boy in the Sauna.
Can place decorative items in the Sauna object, it has slots for it
The Sauna can be styled in Create-A-Style, including changing the colour of the rocks.
The Sauna can be placed anywhere – In- or outside.
Can have steamed vegetables in the sauna
Sauna object also has a bathtub with a rubberduckie. Can have hydrotherapy or a mudbath there.
Outdoor Shower – Sims shower in their swimwear and are not shy with other Sims around, cannot woohoo in it.
Gold Edition
Serenity Retreat lot which has the new massage table, can give amazing romantic, accupuncture, swedish, deep tissue and hot stone massages. Can get a fertility buff from the massage table that gives a higher chance on twins/triplets!
Q&A from the Covert Live during the chat
Guest: Is Sunlit Tides part of Seasons or is this something different
SimGuruSmitty: Hi Guest, This world is something completely different
Michelle: So this is a world you can get with just the base game? or do you need seasons to buy it?
SimGuruSmitty: You do NOT need seasons to get this world. Just base game. ^^
BritneySpears: BOY OR GIRL! YEAH FOR OPTIONS
SimGuruSmitty: This is one of my FAVORITE parts of the sauna!
Hekate Is the roof of the spa new or was already in the game?
SimGuruSmitty: It's new!
Daelia Can we place the mailbox that comes with Sunlit Tides for other builds?
SimGuruSmitty: In other worlds? Yes! — With the Buy Debug cheat. 
beaty are there any new foods?
SimGuruSmitty: Unfortunately not in this world, but I *can* hint there is some fun food stuff coming in the store.
Jason Are any other old families returning or is it just the Pleasants?
SimGuruSmitty: It's just the pleasants this time around.
Rudy I really like the color of the water, it gives such a tropical feeling!
SimGuruSmitty: The water texture is my favorite part of each world. 
They make every world awesome and unique.
SimsFan Is this a Hawaii inspired world?
SimGuruSmitty: It's inspired by a number of island locations. Not entirely hawaii, but it is meant to be a tropical paradise
SimGuruSmitty: South Pacific Island, Hawaii, Fiji, — More South Pacific than Carribbean. is that inspiration.
Ray Would it be possible to woohoo in those showers?
SimGuruSmitty: @Ray nope!
AlexBellant Question: Do all these premium content come with the World when you buy it? or do you have to buy it separate ?
SimGuruSmitty: They come with the world when you buy it. The Sauna comes with the world. The Sauna, Spa Retreat and Massage table come with the GOLD version of the world.
catchyseachild So it's limited to young adult and up? No teens?
SimGuruSmitty: Maybe?
SimGuruSmitty: We think they can, but we don't remember right now. :/
jacqpinks can the outdoor shower be placed inside and work the same way as the inside ones
SimGuruSmitty: Yes. It doesn't work exactly the same. You can put them inside, but the Sims switch to swimwear to use the shower.
Peter seriously what is the difference between the normal version and the gold version of the world? is it just the objects
SimGuruSmitty: Gold Version – World, Sauna, Serenity Retreat, Massage Table
SimGuruSmitty: Standard – World, Sauna
Ryadne24 Can pets come to Sunlit Tides?
SimGuruSmitty: If you have The Sims 3 Pets, then Yes! Pets can come to the island.
Guest How will Seasons work with Sunlit Tides? I dont know how Winter will be with Sunlit Tidess
SimGuruSmitty: Winter *can* exist in Sunlit Tides. It does not have to.
Charlaux Hi,Will there be townies aswell ? (I mean native townies)
SimGuruSmitty: Yes!
SimGuruSmitty: Our townie pool is a mix of natives, vacationers, and permanent non native island folk
Ivory If you select to try for a specific gender, will it actually give you that gender 100% of the time? Or is it just a higher chance of the gender you select?
SimGuruSmitty: It is 100% of the time, if you get pregnant.
Heidi Can a Sim offer the volcano an offering?
SimGuruSmitty: No.
MikeS Was that a reef texture in the ocean?
SimGuruSmitty: Yes!
My Can you have the roof that is on the spa on your house?
SimGuruSmitty: That is currently a rabbit hole texture. So sadly, no.