Drive from Nairobi at 6 am for Mt Longonot National Park, passing through the Kikuyu lush green highlands. A scheduled stop will be made at the Great Rift Valley view point. The Rift Valley is an active volcanic area - you will actually be able to see Mt Suswa and Mt Longonot from this viewpoint.
Then, arrive at the Mt Longonot National Park for your hike up to the crater. You can make some rest stops at the designated places on the trek. You will get to the rim of the crater and look into the awesome crater below. If you have the strength for it, you can go round the rim of the crater.
Descend from Mt Longonot to the base at the Park headquarters. Relax for a while and have lunch at Marina Camp by the lakeside. Go on an hour-long boat ride during which you will see many birds, including the diving African fish eagle. You will also go to the hippo pool and see the hippos as they swim in the water while opening their mouths to over 180 degrees. Afterwards, you will be dropped off at your Nairobi hotel/apartment/residence.