Hello! That sounds like an exciting trip. Let's dive into some travel tips for your journey.

Best Time to Visit:
Surabaya, Malang, Bromo, and Ijen are beautiful all year round, but the weather is most favorable from May to September, as it's the dry season. The fluctuating climate at higher elevations, such as Mount Bromo and Ijen Crater, is unpredictable, so it's a good idea to keep an eye on the latest weather reports.

Route and Accessibility:
You can reach Surabaya through Juanda International Airport which is well-connected globally. From Surabaya, Malang is about two hours away by train or bus. To reach Bromo, it's advisable to book a jeep from Malang or probolinggo, which will also include sunrise viewing. The Ijen Crater can be reached from Banyuwangi, and it's best to book a tour or guide for the same.

Accommodation and Booking:
There is a range of accommodation options in all destinations depending on your budget. It's advised to make your booking in advance, especially during peak season. Homestays, guesthouses and hotels are available. Remember, proximity to tourist spots can drive up prices.

Clothing and Essentials:
Pack light, but don't forget some warm clothing for the chilly temperatures in the mountains. Sunscreen, hats, and sunglasses are a must to protect against the sun. For Bromo and Ijen treks, comfortable walking shoes are essential. Include a raincoat or umbrella as sudden showers are common.

Health and Safety:
Stay hydrated and carry personal medication, if required. Follow the instructions from local authorities and tour guides, always stick to the designated paths during your treks. For Bromo and Ijen, gas masks are provided by tour operators, make sure to use them.

Local Etiquette and Respect:
Indonesians are friendly and welcoming. Treat locals with respect and abide by local customs. It's considered polite to ask permission before taking photos of people or religious events. Remember to dress modestly, especially when visiting religious sites.