If you're hoping to visit Africa's Largest lake while in Kenya you're in luck. On the west side of the country lies the city of Kisumu, which is situated on the shores of the great Lake Victoria. Kisumu is Kenya's third largest city and the second largest and influential on the lake after Kampala, Uganda.
With an airport and direct flights to Nairobi it's easy to get to as a starting or ending point for those heading out to Maasai Mara Reserve.
While in Kisumu, it's a must to get on the lake to go fishing, spot some hippos or do some bird watching along shoreline. A quick google search for day trips on the lake will result in a few companies with bad email communication charging anywhere from $100 to $400 per person.
This was my experience trying to organize for 8 people in December of 2019. So unless you are okay with those prices I would suggest doing things the old fashioned way and heading straight to the lake to organize your trip on the water. There are two locations where you can find boats that will take tourists out for a short day trip.
Hippo Point
Dunga Beach
Either of these locations is only a few minute tuk tuk, taxi or motobike ride from town. There will be men waiting to take passengers out. You can expect to pay around $40 - $50 USD per head. It will depend on your group size, boat size and personal bargaining skills. Don't expect much except friendly Kenyan drivers doing their best to spot the Hippos.
Morning is supposedly the best opportunity to see the hippos however we left around midday and were treated to a bloat of hippos.