First time in Mombasa
On a first visit with one full day, book Fort Jesus, Old Town, and Haller Park. With only a morning, book the half day and skip Haller Park. Leave the marine park or a Nyali beach for a second day.
One day, then a second day
Day one is the full-day tour: fort, lanes, seafront if the clock allows, then Haller Park. Day two is either the marine park or a Nyali day. Swapping that order leaves the main monument for a tired afternoon.
Read the fee category before you queue. The passport or identity card decides the column on the prices page. Dress using the Old Town clothing rules. If you are also landing at Moi International Airport the same morning, say so. A tight connection from the aircraft to the fort is rarely pleasant. The pickup page is the place to separate the transfer from the tour.
Questions
What should I do on my first day in Mombasa?
Fort Jesus, Old Town, and Haller Park if you have about 8 hours. Fort Jesus and Old Town if you have about 4.
Do I need a guide?
You can buy a Fort Jesus ticket and go in alone. A guide is how the Old Town lanes and the day's timing stay coherent.
How many days are enough?
One full day covers the city core. A second day covers the reef or the beach.

Full-day Mombasa tour
Half-day Mombasa city tour