This will be a highlight of the trip! It is a unique stop. The dead sea is actually a salt lake bordered by Jordan to the east and Israel and the West Bank to the west. Its main tributary is the Jordan River. (There are many similarities to the geography of the Holy Land and Utah.)
It is 1,412 ft) below sea level, the lowest place on earth! Its salinity is 34.2% and is one of the world's saltiest bodies of water, being 9.6 times as salty as the ocean. Its high density makes swimming similar to floating. This salinity makes for a harsh environment in which plants and animals cannot flourish, hence its name.
The Dead Sea has attracted visitors from around the Mediterranean Basin for thousands of years. It was one of the world's first health resorts (for Herod the Great), and it has been the supplier of a wide variety of products, from asphalt to fertilizers to beauty products.
The Dead Sea is receding at a swift rate but can still take advantage of its salty waters ad & high mineral content.
A basic understanding of Israel as a country will help you better understand some of the things you will experience when you there. For example, you may want to study more about the history of Israel (here is a youtube link to a friend's basic summary of the Old Testament history and scattering of the House of Israel). And there are other history books and resources that will be helpful to you.
However, we are living at a time of the gathering of Israel. That creates some dilemmas for latter-day saints and how they see Israel today. Although, it is a 'holy land', it is also a very 'political land' that gathers the attention of the entire world.
Consider this article that gives a basic history of the Arab-Israeli conflict and how we might see it more clearly.
https://www.churchofjesuschrist.org/study/ensign/1971/01/arab-israeli-conflict?lang=eng
Since you don't have a camel, you will have to get good carrying your own things on and off the bus, and between sites and hotels. Although you will leave large luggage at the hotel, many participants like to carry a basic day bag with them as they travel each day to the sites. Such a bag is helpful to carry:
Scriptures, journal, camera, tiny flashlight, guidebook, water, snacks, necessary medications, warmer clothing to layer, small umbrella, and money.
But don't carry too much, slimmer the better, because you will have it with you all day. You will want to be unencumbered and hands free. Too much stuff can be a burden.
Bring comfortable headphones (earbuds) that can be plugged into a 3.5mm audio jack. You will use them much of the day as we travel from site to site with our whisper quiet communication headsets.
Handkerchiefs or tissues, small umbrella, tiny flashlight, small sewing kit, and travel alarm could also be helpful.
Traveling with a small amount of prescription medications should not be a problem, but bringing a copy of your prescription might be helpful, just in case. Pharmacies are also easy to find in Israel, if needed, but you may also want to bring some basic over the counter medications like pain reliever, cold medicine, diarrhea medicine, etc. (sometimes new foods, culture, and travel can cause changes in digestion) to have at your convenience.
DON'T PACK TOO MUCH. If you really need a toiletry or other convenient item, we can usually find it in Israel. Almost always participants overpack, so choose essential items over convenience. Plus, you will want some room in your bags for any souvenir items you buy in Israel.