I separated the suggested activities as European and Anatolian side activities due to the unique feature of our Istanbul bridging two continents together. As I live on Anatolian Side I would like to start suggesting options on this side! 🙂
The Prince’s Islands

Islands have always been at the top of our list of places we most enjoy as a family to do on a weekend in Istanbul. We usually prefer to visit the Islands on Saturdays as soon as it starts warming up in the spring. On Sundays it becomes very crowded on the Islands like many other places in Istanbul. It is easy to get to the Islands – you can reach any island by catching a ferry or small ferries from Bostanci (it would be Kabataş pier if you live on the European side). Although there are five large islands (Kınalı, Burgaz, Heybeli, Büyükada and Sedef) we usually go to Büyükada or Heybeliada. These islands used to be the exile destination for princes in ancient times but today you can enjoy fresh mussels and fish, take a ride on horse carriages or ride a bike to see the island. It could also be fun both for you and your children to feed the seagulls with simit (a traditional Turkish sesame bagel) on the boat you will catch towards the island of your choice.
The Toy Museum
The Toy Museum is located in the Göztepe district in Istanbul and was founded by the poet Sunay Akın. It has a wonderful collection of some of the most beloved toys in the history of toys going all the way back to 1700’s. Regardless of your age, you will enter a world of mystery where you will be excited to find something of your childhood and more! J We also enjoyed ourselves a lot when we saw the amazing set of 4000 antique toys collected from all around the world in the “land of toys” called museum. The museum has many activities and seminars to choose from.
Göztepe Park
Right after your visit to Toy Museum you can easily reach (2 minutes away from the museum by car) Göztepe Park which is another place of great joy for families. Since we are surrounded by massive buildings all the time in Istanbul, the reverse sense of peace you feel in Göztepe Park is unavoidable. I think Göztepe Park is the best, most fun and probably largest park on the Anatolian side with its walking trails, bicycle routes, picnic spaces, ponds, fountains, many children activities, and its room for concerts and myriad other activities.
Nostalgic Tramway / Kemal Usta Waffle / Baylan Kup Griye

A little bit smaller version of the tram on Istiklal is the one that runs between Moda and Kadıköy. Riding around Moda with your children can be bundles of fun for the whole family.
While you are on it, stop by Kemal Usta to eat a waffle. I want to emphasize that you really shouldn’t skip it. You can find waffles in almost every corner these days butttt it is even a pleasure to describe your waffle when you order it! J “Wild orange”, “Sleepless Nights” (has clotted cream!), “Crazy caramel”, “Lemon the sourest”, “Figs, look it is green”, “Seducing power” (almond paste), “Uncontrolled energy” (fig marmalade) and chocolate sauces they use make your waffle unique… This is the only place where my anti-fruit kids can be reasoned with and they gulp it all down. 🙂
Another legendary delicacy you cannot forget in Kadıköy is Kup Griye. Kup Griye is a patented product by Baylan Patisserie and served as a mixture of vanilla and caramel ice cream topped with whipped cream and caramel sauce with a slice of a lady finger that kids just literally eat up. It is a killer desert, I highly recommend it if you happen to be around Kadıköy.
Darica Zoo and Botanical Park
Just like our trips with our children abroad when you always stop by at the zoo, I suggest you do the same in Istanbul with your children. Since the park covers large grounds it would be wise to visit the zoo in spring or autumn when the weather is nicer and it doesn’t rain. Warm summer days can be a bit tricky to this massive park though, and now you know it too. J You can check the activities of animals announced on the “activity board” located by the entrance and plan your visit.
Since we’re already here, let’s talk about the places you would like to take your children on the European Side… Those who live on the European side have the upper hand in terms of variety of places as opposed to those who live on the Anatolian side. I couldn’t decide where to start but my children are always there to help of course. The list below is totally made by their choices. Here we go
İsfanbul

We have actually visited theme parks multiple times abroad because I work at Turkish Airlines even my children are quite young. İsfanbul is the first theme park in Türkiye and we went there right at the beginning of September before schools started and just loved it. It is as nice as Disneyland and does not charge you an arm and a leg. After you make your payment – they have family tariff – you wear your bracelets and enjoy all kinds of activities until the park shuts down in the evening. If you enter in the morning you don’t waste time queuing but enjoy the park at its best and participate in any activity or game of your choice as long as you like. Some games have “height limitations” like theme parks abroad have too, just so you know! It is absolutely guaranteed that you get wet in the “Çılgın Nehir” (Crazy River) and “Viking” sections and that you’ll have your heart in your mouth as a parent in “360”:). There are dryers outside located to dry you up.
After lunch, I highly recommend that that you have a cup of Turkish coffee accompanied by delicious Turkish delights at “Bir Zamanlar Istanbul” if you have time.
Istanbul Aquarium
The Aquarium is a fun fun fun place to spend time with your children with its organized attitude, variety of its sections and activities. After you pay the entrance fee they take your photo which they will play with a little. Don’t forget to strike a pose and pick it up on your way out. 🙂 After that you can start floating through the mysterious world of the seas. If you keep an open ear listening to the announcements you can see the fish being fed. And of course if you have diving license and the guts (!!) to do it, you can dive into the aquarium with the sharks. 🙂
Istanbul Dolphinarium
You will not only meet smart and cute dolphins but very large (I mean it) walrus and seals in this performance center located in Eyüp. The show is a lot of fun especially for your children. If they can swim too then they can jump into the water to swim with dolphins. You can also buy discounted entrance tickets if you check some of the internet “deal of the day” sites.
Miniatürk
As far as I know Miniatürk is the only place where you can visit all the historically important structures and buildings in Türkiye at once. Everything is brought together here so if you didn’t get a chance to see it before you can see some great sites here, including Balıklı Göl (Pool of Sacred Fish) in Urfa, the Roman Bridge in Adana, the Çanakkale Monument of Martyrs, and the Tomb of Rumi in Konya. You can wave at the miniature planes at the Istanbul Atatürk Airport, and walk over Bosphorus Bridge without running the Eurasia marathon this time. Believe me, we crossed over the bridge more than a few times. 🙂
Istanbul Aviation Museum
For kids who have a burning interest in planes, a visit to the Aviation Museum in Yeşilköy the only cure! 🙂 It is possible to see all kinds of planes such as propeller planes, helicopters and many others. Some children find it especially exciting to learn that all the planes outdoors have been used by Turkish Air Forces. The museum also has memorabilia of people who have left their signature marks on the pages of aviation history, different types of engines from different types of planes, several different armaments and clothing and uniforms used throughout history.
Other than all of the above suggestions, it would be a shame not to include a classic tour of Istanbul since these attractions are not to be missed by anybody: Grand Bazaar, Blue Mosque, Haghia Sophia Mosque, Basilica Cistern (you know, even Dan Brown mentioned these places in his books, so don’t miss them :), the Obelisk and of course Topkapi Palace.