Unfortunately unlike airlines, cruises don't offer infants under 2 automatic free tickets. Depending on the cruise you choose you could be spending upwards of $1000 for your child to cruise with you. Who wants to do that? Not me! So how can your child cruise for free?
Cruises are always offering promotions! One promotion that a lot of cruises offer is the 3rd and 4th guest cruise free or kids cruise free with the purchase of 2 adult cruises. All you have to pay is the taxes, which is the same for booking international flights for lap infants under 2. The taxes vary per cruise, I have seen this as low as $99 and as high as $349 per person.
The day you look to book your cruise this promotion may not be available but keep checking, it will most likely come up. Cruises are always offering promotions and I suggest checking once a week to see if this one has been added. Even if you book the cruise without the promotion and it comes up you can call in and they will apply the promotion and lower your balance owed.