As of my last knowledge update in September 2021, here are some of the most expensive trips and experiences in the world. Please note that prices and offerings may have changed since then. Always double-check with current sources before making any travel plans:

1. Space Tourism: Taking a trip to space with companies like Blue Origin or Virgin Galactic comes with a hefty price tag, ranging from hundreds of thousands to millions of dollars.
2. Submarine Expeditions: Deep-sea submarine trips to explore the ocean’s depths can cost several tens of thousands of dollars.
3. Antarctic Expeditions: Luxury cruises and tours to Antarctica can range from $10,000 to over $100,000, depending on the level of comfort and activities included.
4. Private Yacht Charters: Chartering a private yacht for a luxury cruise can easily run into the hundreds of thousands of dollars.
5. World Cruises: Booking a spot on a world cruise, which can last several months and visit multiple continents, can cost upwards of $100,000.
6. Luxury Safari in Africa: High-end safari experiences in Africa can cost tens of thousands of dollars, offering exclusive accommodations and personalized wildlife encounters.
7. Private Island Retreats: Renting a private island for a vacation can range from tens of thousands to millions of dollars, depending on the location and amenities.
8. Exclusive Resort Packages: Some luxury resorts offer packages that include private villas, personal butlers, and extravagant amenities, often priced at tens of thousands of dollars per night.
9. Trans-Siberian Railway in Luxury: Traveling the Trans-Siberian Railway in lavish, private compartments can cost a significant amount due to the length of the journey and the exclusivity.
10. Polar Bear Viewing in the Arctic: Specialized tours to see polar bears in their natural habitat can cost several thousand dollars.
11. Superyacht Adventures: Renting a superyacht for a sea adventure can come with a multi-million-dollar price tag.
12. Exclusive Ski Resorts: Staying at ultra-luxury ski resorts during the peak season can lead to high costs due to accommodation, activities, and services.
13. Private Jet Tours: Tours that take you around the world on a private jet with extravagant accommodations and experiences can be priced at several hundred thousand dollars or more.
14. Culinary Tours: High-end culinary tours that offer private chef experiences, wine tastings, and gourmet meals can be quite expensive.
15. Cultural Immersion Tours: Exclusive trips that allow you to immerse yourself in indigenous cultures and traditions can be priced at several thousand dollars.

Keep in mind that prices can vary widely based on factors like location, duration, level of luxury, and services included. It’s also important to consider that the travel industry is subject to changes, so the availability and pricing of these experiences may have evolved since my last update.