Extreme Watersport

SANTI BZ420X Heated Undersuit

The SANTI BZ420X Heated Undersuit is SANTI’s flagship active heating drysuit undersuit, designed for technical, CCR, cave and expedition divers who need reliable warmth during extreme cold-water dives. Combining the insulation of the BZ420X platform with integrated heating elements across the torso, thighs and arms, it delivers active thermal support when passive insulation is no longer enough.

Built as part of the SANTI external battery heating system, the BZ420X Heated is designed to work with a SANTI Thermovalve or SANTI Connector and an external battery. This configuration keeps the battery outside the drysuit while providing powerful, controlled warmth for long dives, decompression stops and demanding cold-water conditions throughout Australia.

110W Active Heating External Battery System Built for CCR & Technical Diving
SANTI BZ420X Heated Undersuit

Choose Your Size

$1,980.00
Most SANTI BZ420X Heated undersuits are supplied to order directly from SANTI. Please allow approximately 6–10 weeks if your preferred size is not currently available. Contact us for current availability, sizing advice or made-to-measure options.
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Product Highlights

Ultimate Active Heating for Extreme Cold-Water Diving

The SANTI BZ420X Heated combines maximum passive insulation with an integrated active heating system, making it one of the most advanced thermal solutions available for drysuit diving. New heating cable placement provides more even warmth distribution, while the smooth inner lining improves donning and doffing.

Designed for long technical dives, CCR diving, cave exploration and extreme cold-water conditions, the BZ420X Heated delivers warmth when it matters most while retaining full insulating performance even when the heating system is switched off.

Key Features

Key Features

Integrated Heated System

Heating elements positioned across the torso, thighs and arms provide active warmth during long cold-water dives.

External Battery Safety

Designed for use with SANTI Thermovalve or Connector and an external battery, avoiding the risks associated with internal batteries.

Even Heat Distribution

Updated cable layout improves heating efficiency and provides more consistent warmth throughout the undersuit.

Warm Even When Off

Retains excellent insulating performance even when the heating system is not activated.

Technical Details

Technical Specifications

The SANTI BZ420X Heated is a premium heated drysuit undersuit designed for demanding technical and expedition diving. It combines upgraded passive insulation with an integrated active heating system, delivering warmth, comfort and reliability for extreme cold-water environments.

Heating Power
Maximum heating power: 110W.
Heating Temperature
Maximum heating temperature: 45°C.
Battery System
Designed for SANTI external battery systems using Thermovalve or Connector.
Heating Zones
Heating elements positioned on the torso, thighs and arms.
Runtime
Approx. 3 hours with 24Ah battery, 1.5 hours with 14Ah BluePower, or 3 hours with 28Ah BluePower.
Protection
Temperature and overcurrent protection included.
Best Suited For
Technical diving, CCR diving, cave diving, expedition diving and extreme cold-water decompression dives.
Sizing
Available in men's and women's standard sizes, with made-to-measure options available.
Weight
Approximately 2.6 kg in men's size L.
Important Compatibility
Works only with SANTI Thermovalve or SANTI Connector.
Included

What's Included

  • SANTI BZ420X Heated Undersuit
  • Integrated heating cable system
  • SANTI manufacturer's care information

External battery, SANTI Thermovalve and Connector are sold separately unless otherwise stated.

Size Guide

Need Help Choosing Your Size?

Use the size guide below as a reference before ordering. If you are between sizes or plan to wear additional base layers, contact us and we can help recommend the most suitable fit.

Men’s Size Guide

SANTI BZ420X Heated Undersuit men’s size guide

Women’s Size Guide

SANTI BZ420X Heated Undersuit women’s size guide

Why Choose the SANTI BZ420X Heated?

The SANTI BZ420X Heated is designed for divers who need more than passive insulation. By combining the flagship BZ420X thermal platform with integrated active heating, it provides reliable warmth during long cold-water dives, technical dives, CCR profiles, cave exploration and extended decompression schedules.

Unlike standard drysuit undersuits, the BZ420X Heated actively supports thermal comfort by distributing heat through key areas of the body. Heating elements positioned across the torso, thighs and arms help maintain warmth during long periods of reduced movement, such as decompression stops or CCR diving.

External Battery Heating for Technical Diving

The BZ420X Heated is part of the SANTI external battery heating system. It is designed to be used with a SANTI Thermovalve or SANTI Connector and an external battery, keeping the power source outside the drysuit. This setup is preferred by many technical divers because it avoids placing batteries inside the suit while still delivering powerful active heating.

Built for Melbourne, Victoria and Extreme Cold-Water Diving

For divers completing long technical dives in Melbourne, Port Phillip Bay, Victoria, Tasmania and other cold-water environments across Australia, maintaining warmth can become a major factor in comfort, focus and dive performance. The BZ420X Heated is designed for these demanding conditions, especially when dive duration, decompression time or low activity levels make passive insulation alone less effective.

BZ420X Heated vs Standard BZ420X

The standard BZ420X is SANTI's flagship non-heated drysuit undersuit, offering maximum passive insulation. The BZ420X Heated takes that platform further by adding integrated active heating, making it the stronger choice for divers regularly completing extreme cold-water, CCR, cave or expedition dives where active warmth provides a significant advantage.

Why Buy Your SANTI Heated Undersuit from Extreme Watersport?

Extreme Watersport is an authorised SANTI dealer in Australia, providing genuine SANTI heated systems with experienced product advice. We can help you compare the BZ420X Heated with the standard BZ420X, Flex 190, KANGO and SANTI heating accessories, ensuring your undersuit, battery and drysuit setup work together properly for your diving conditions.

FAQ

SANTI BZ420X Heated Undersuit FAQ

Who should choose the SANTI BZ420X Heated?

The BZ420X Heated is designed for divers who need active warmth during demanding cold-water dives, including technical divers, CCR divers, cave divers and expedition divers completing long bottom times or decompression schedules.

Does the BZ420X Heated include a battery?

No. The BZ420X Heated is designed to be used with a SANTI external battery system. Battery, Thermovalve and Connector options are usually supplied separately unless specifically included in a package.

Can the BZ420X Heated be used without turning the heating on?

Yes. The BZ420X Heated retains strong insulating performance even when the heating system is switched off, making it a capable cold-water undersuit even without active heating.

What is the difference between BZ420X and BZ420X Heated?

The standard BZ420X is SANTI's flagship non-heated undersuit. The BZ420X Heated adds an integrated active heating system with heating elements positioned across key areas of the body, making it better suited to extreme cold-water and long-duration technical dives.

Is the BZ420X Heated suitable for CCR diving?

Yes. The BZ420X Heated is particularly well suited to CCR, cave and technical diving where long dive times, reduced physical movement and extended decompression can make active heating valuable.

Do you offer made-to-measure sizing?

Yes. SANTI offers standard men's and women's sizing as well as made-to-measure options. Contact us for sizing advice before ordering.

Need Help?

Need Help Building a SANTI Heated System?

Choosing a heated undersuit requires more than selecting a size. The BZ420X Heated must be paired with the correct SANTI battery, Thermovalve or Connector setup for your drysuit and dive plan. Our team can help you choose the right heated system for technical, CCR, cave and cold-water diving.

Contact Us for Advice