Hi,
When I use the camera underwater (28 degree Celsius) I can easily make 150 pictures a day for at least 2 days. (No use of internal flash) Then I did recharge it, cause I don't like the experiance under water without bat-power during my holiday.
Above Water in 30 degree celsuis environment I made maybe 200 to 300 pictures with one battery fill splitted up through several days.
In other words the battery is excellent and it last long enough. As I usually use an external flash (above and underwater) the battery of the camera has never been a problem to me. If you have access to power during the night just charge it for the next day. I did think about buying a 2nd spare battery just in case and it might be recommended.
Best regards,
Chris