In the morning, hike through the Sanjay Gandhi National Park to reach the Kanheri Caves. These ancient Buddhist rock-cut caves date back to the 1st century BCE and have over 100 intricately-carved caves. Afternoon, enjoy lunch at the park's cafeteria and then head to the Global Vipassana Pagoda, a massive meditation dome. Evening, visit Film City, a renowned film studio complex and take a guided tour of the sets and soundstages.
Start your day early by heading to Madh Island for surfing lessons. The beaches here are ideal for beginners and the instructors will provide all the gear you need. Afternoon, rent a bike and explore the quaint villages and beaches on the island. Evening, visit the Versova Beach, famous for being one of the cleanest beaches in Mumbai and grab some street food at the stalls nearby.
Take an early morning flight to Murudeshwar and then a boat to Netrani Island, a hidden gem for scuba diving. Dive into the clear waters and explore the vibrant coral reefs and marine life. Afternoon, enjoy lunch on the island and then head back to Murudeshwar to visit the Murudeshwar Temple, a Hindu temple with a 237.5 feet tall Lord Shiva statue. Evening, catch a flight back to Mumbai.
If you have an extra day, take a day trip to Lonavala and visit the Karla Caves. You can also go bungee jumping at Della Adventure Park in Lonavala. To maximize your fun, try the street food in Mumbai, such as vada pav and pav bhaji, and take a Bollywood tour to learn about the Hindi film industry.