List of Supported Timezones
PHP Manual

Pacific

Pacific
Pacific/Apia Pacific/Auckland Pacific/Chatham Pacific/Chuuk Pacific/Easter
Pacific/Efate Pacific/Enderbury Pacific/Fakaofo Pacific/Fiji Pacific/Funafuti
Pacific/Galapagos Pacific/Gambier Pacific/Guadalcanal Pacific/Guam Pacific/Honolulu
Pacific/Johnston Pacific/Kiritimati Pacific/Kosrae Pacific/Kwajalein Pacific/Majuro
Pacific/Marquesas Pacific/Midway Pacific/Nauru Pacific/Niue Pacific/Norfolk
Pacific/Noumea Pacific/Pago_Pago Pacific/Palau Pacific/Pitcairn Pacific/Pohnpei
Pacific/Ponape Pacific/Port_Moresby Pacific/Rarotonga Pacific/Saipan Pacific/Samoa
Pacific/Tahiti Pacific/Tarawa Pacific/Tongatapu Pacific/Truk Pacific/Wake
Pacific/Wallis Pacific/Yap      

List of Supported Timezones
PHP Manual