Many mature travelers enjoy cruise vacations. By searching the web and online forums you can find a lot of information and recommendation on cruises that are of interest to you. One site is cruisecritic.com and seniortravel.about.com.
You can find information on single senior cruises for your grandmother by seeking travel agents who specialize in senior vacation packages. Very few general travel agents or online booking sites offer this service.
Many travel agencies offer cruises that are aimed towards seniors. For some examples online you can visit www.americandiscountcruises.com/senior-citizen-travel.html
Many cruise offering companies provide senior discounts. Here are some senior discounts from Carnival Cruises: http://www.cruiseone.com/travel/editorial.jsp/edType/Custom Page/pagename/Carnival_Senior_Specials?. Also, here is some more information on senior discounts for cruises: http://www.cruisecheap.com/cruises/senior-discounts.html
This website http://seniortravel.about.com/od/cruises/Senior_Travel_Cruises.htm has a lot of information about cruises and specifically for seniors. It also has links on the website to re-direct you to book a cruise after reading all the information. All general questions can be answered on this website.
Senior citizens get discounts on many cruiselines. Travel agencies also have specific discounts for senior citizens looking to cruise.
Carnival Cruise lines does offer a Senior discount. www.cruisesandseniors.com has a list of the most senior friendly cruises and it also helps you to find the best prices on senior cruises. Cruisesandseniors.com also offers information to help senior travelers find the best cruise for their needs.
There are several cruise lines that hold senior cruises and offer discounted rates. To compare prices, check out http://www.mustcruise.com/cruise_info/seniors.html, or http://odysseys-unlimited-catalog.com/Senior Travel Cruises.html?gclid=CMPUjqb7_qkCFUTBKgodCWNAxw
Many cruise lines cater to senior citizens. HAL, Costa and Celebrity are a few. You can find all the information you need here: http://seniors-site.com/travel/cruises.html
Visit their website. There is a lot of information about their cruises, pictures from past cruises, and prices for upcoming cruises. Also, read reviews from different travel magazines.
Most retired seniors enjoy traveling on cruises. This allows them to relax; however, they can see many places without have to travel in and out of multiple airports.
Riverboat cruises information can be found several places. There is always the internet, travel agencies, or even books about the cruises in your library.
Check out different travel agencies for information on senior travel. If you can't find the best information then contact a local senior home and ask them if there's any good information they can tell you about senior travel.